On May 29, a young woman named Bushra al- Maqtari joined a group of several thousand protesters marching down a trash-strewn boulevard in the Yemeni city of Taiz. The Arab world’s democratic uprising was five months old, and patience among the protesters in Taiz — Yemen’s second largest city — was wearing thin. Maqtari had been one of the first and most fearless leaders of the movement. She is a remarkable figure: a 31-year-old university administrator and fiction writer, she is also a childless divorcee who refused, until recently, to wear the abaya, the all-covering gown that is practically mandatory for women in Yemen. Tiny and frail, she has a round, lovely face, with level brows and tranquil brown eyes.

On that afternoon, Maqtari was standing in a crowd gathered around the city’s General Security building — an imposing six-story edifice flanked by guards — when she heard cracking sounds. She looked up and saw that the officers on the building’s roof were not just throwing rocks, as they had in the past. They were firing straight down into the crowd below. Within minutes, at least four people were dead and about 60 were wounded. Maqtari began running back toward “Freedom Square,” the intersection where thousands of protesters had been camped out for months demanding the resignation of Ali Abdullah Saleh, Yemen’s strongman president. Then the real assault began. Armored vehicles, tanks and bulldozers began converging on the protesters’ tent city from all sides. They fired tear gas and water cannons into the square and began shooting protesters at point-blank range. They doused the tents, which extended for hundreds of yards in every direction, with gasoline and lighted them on fire. None of the protesters had weapons. “People were dying all around us, and there was nothing we could do,” Maqtari told me. Some were burned alive. At around 11 p.m., Maqtari fled to her sister’s house, about 200 yards uphill from the square. There, she and other protesters watched as flames engulfed the entire square, raging for several hours. Officers stormed through the local hospital and several field clinics where protesters were being treated, firing tear gas down the corridors, shooting up the ceilings and arresting doctors and nurses. Some thrust their gun butts into patients’ wounds. Others were laughing hysterically, as if they were on drugs, Maqtari and others told me, and shouting into the darkness, “Ali is your god!” The next morning, amid the charred remains of the tents, someone had scrawled a sardonic reversal of the protesters’ chants on a wall. “The regime wants the fall of the people,” it said.

The massacre in Taiz received little attention in the West, blending in with the larger chaos and violence enveloping the Arab world. In Syria, tanks were rolling through the streets of several cities, as months of protest evolved into a bloody national insurrection. In Libya, the civil war was festering into a grim status quo, with NATO airstrikes unable to dislodge Col. Muammar el-Qaddafi from his Tripoli stronghold. Even Egypt and Tunisia seemed endangered, with fresh violence breaking out and their economies in tatters.

Yet the events in Taiz took on a tragic dimension that went beyond the numbers of dead and wounded. Taiz is Yemen’s least tribal city, home to the highest number of educated people, professionals and traders. The city was “the heart of the revolution,” in one popular refrain, and its protesters were less politicized and more rigorously nonviolent than elsewhere in Yemen. The attack on May 29, with its deliberate cruelty and excess, confirmed what many Yemenis feared: that Saleh sees the democratic uprising as a greater threat to his power than Al Qaeda. The burning of the Taiz square, after all, coincided with the collapse of all government authority in large areas of south Yemen, where heavily armed jihadist groups have captured two towns and several villages. In the northwestern province of Saada, too, a militia movement now reigns supreme; they recently elected Yemen’s biggest arms dealer as their new governor. All this has implications that go well beyond Yemen’s remote mountains and deserts — the chaos in the north, for instance, threatens to set off a proxy conflict between the region’s two great nemeses, Saudi Arabia and Iran — and the Yemeni military has done little to oppose any of it.

Even after Saleh was flown to a hospital in Saudi Arabia in early June, wounded in a bomb blast at his palace mosque, his government — or what is left of it — seemed determined to crush the unarmed protesters while leaving the rest of the country open to some of the world’s most dangerous men. After decades of backdoor collusion with jihadis and armed rebels of all kinds, Saleh and his generals may believe they can more easily defeat these warriors, or make deals with them. If so, they are taking an enormous risk, one that could have deadly consequences for the United States, which has become the chief target of the Al Qaeda franchise in Yemen. It could also prove disastrous for the greater Middle East, now faced with the prospect of a Somalia-style collapse on its southern flank. For 23 million Yemenis, the risk is even greater. If the country continues to disintegrate, they will lose a chance to finally rise above the violence and chaos that have ruled their lives for so long. “They are still attacking us every day, targeting the activists’ houses, arresting people,” Maqtari told me. “It’s as if they are pushing us and pushing us to take up violence, so that we will be like them. They want to turn the revolution into a tribal war. And this will tear the country apart.”

In a sense, the counterrevolution in Yemen began with a single word: baraghala. It is an old Yemeni word, used by northern tribesmen to denigrate the citified, unarmed people of Taiz and its environs. Its meaning is something like “weakling,” but with the negative force of “nigger.” Starting in early February, Saleh and his subordinates began sending out flocks of young thugs to the protest sites, where they would shout, “Baraghala!” at the demonstrators as they beat them with batons. The word did not come as a surprise. Saleh is himself a northern tribesman with an elementary-school education, a manipulative ruler who has shredded his country’s few civil institutions during his 33 years in power. He is widely said to resent Taiz, which was once Yemen’s capital, for its role as a beacon of education and enlightenment. By attacking it, he and his commanders seemed to be deliberately provoking Taizis to abandon their moral high ground and fight back.

“Some of us were thinking of calling it the Revolution of the Baraghala,” Maqtari told me when I met her for lunch on my first day in Taiz. We sat at a long table loaded with roast chicken and a spicy lamb stew called fahsa, in a bustling restaurant owned by a sympathetic businessman who had helped feed the protesters. She wore a black-and-white-flecked head scarf wrapped tightly around her face, and she had with her a group of fellow protest organizers whose polite, manicured appearance and career profiles all hinted at the city’s distinct identity: a doctor, a lawyer, a graduate student, an engineer. Taizis are intensely proud of their civil roots, Maqtari told me. The city is an ancient center of trade, cradled by high green mountain slopes where coffee grows. It is just northeast of the ancient Red Sea port of Mokha, for which the coffee drink is named, and the relative cosmopolitanism of its merchant classes helped dissolve the power of the tribes long ago. The area is known to Yemenis as balad al aish — the country of living — in contrast with the north, which is called balad al jaish, or the country of the army. It has always been vulnerable to raids by tribesmen from the arid northern mountains. Taiz was once an attractive city, but it is now battered and decayed, even by the standards of Yemen, the Arab world’s poorest country. For three decades, Maqtari told me, Saleh has systematically starved the city of capital, while focusing his patronage network on Sana. “It is like a kind of racism,” Maqtari said. “He wants Taiz to suffer because of who we are.”

After lunch, one of Maqtari’s friends drove us to the square. The streets reeked of overflowing garbage; residents told me the government had barred municipal workers from collecting it. The lines of cars waiting to buy gasoline went on as far as the eye could see, blocking the city’s main roads. We passed several checkpoints where the guards were dressed in plainclothes; many are said to fear assassination since the attack on the square. Only one checkpoint had a full complement of uniformed soldiers, near a huge poster of the president. “They are here to guard the poster,” Maqtari told me as the guards waved us through. “It’s the only one left in Taiz.”

We stopped near Freedom Square and walked the rest of the way. The streets were littered with blackened tent fragments, chunks of concrete and shell casings. Even the trees had been burned, their trunks charred and their uppermost leaves shriveled and brown. As we reached the center of the square, a few dozen teenagers and children ran up to us, greeting Maqtari as if she were the Pied Piper. Then something remarkable happened: The Yemeni national anthem began playing from a tinny loudspeaker nearby. Instantly, everyone in the square stood at attention, raised their right hands in a peace symbol and sang along. I had never seen this anywhere in Yemen. Afterward, Maqtari explained that this had been a regular ritual during the sit-in, along with moments of collective silence. “We wanted to show that patriotism does not belong to the regime,” she said.

Moments later, thick clouds darkened the sky, and a heavy rain began pelting the streets into mud. We ran for shelter under the eaves of a burned building, and one of Maqtari’s colleagues drove up in a battered brown sedan. They wanted to take me up to the mountains for a view of the city. Eight of us piled into the car, four men and four women, packed in tightly together — a shocking breach of decorum for most Yemenis, but here in liberal Taiz, it was, apparently, perfectly natural. As we drove through a blinding downpour, Maqtari talked about her love of the novels of José Saramago, Jorge Amado and Milan Kundera. She has published one story collection of her own and is working on her first novel. “I’m a bookworm,” she said, and described to me how she flies to Cairo whenever she can afford it and comes home with suitcases full of books in Arabic translation. One of her recent favorites — to my amazement — was the letters of Henry Miller and Anaïs Nin, the twin idols of 20th-century literary erotica. It is difficult to convey just how unusual this is in a country where many women are married off by age 13 and most cannot read.

The air on the mountaintop was cool and damp. There was a magnificent view of the terraced hillsides below, with traditional Yemeni mud-brick houses set on escarpments overlooking the city. It is probably the prettiest place in Taiz, but one protester described it to me as “a jewel of ashes.” Maqtari and I sat inside the lobby of an empty hotel and ordered tea. The Taiz protests, she told me, started in January, when a group of young left-wing dissidents were inspired, like their peers in Egypt and elsewhere, by the Tunisian revolution. Most of them had grown disillusioned with Yemen’s opposition political parties, which have made tacit deals with Saleh in order to maintain their paltry share of power. They began organizing demonstrations, using the slogan popularized in Tunisia and Egypt: “The people want the fall of the regime.” Yemen’s largest opposition party, an Islamist group known as Islah, demanded that they modify the slogan and ask for “reform” of the regime. The protesters refused. Maqtari wrote a series of strident columns for the one local paper willing to publish her. On Feb. 11, the day Mubarak fell, the protests in Taiz swelled to tens of thousands and turned into a permanent sit-in at the intersection that became known as Freedom Square. “We never expected that many people to join us,” Maqtari told me. Taiz seemed to be seeding all of Yemen with its spirit. Taizis have been at the core of local protest movements in several other cities, including the capital. After gunmen opened fire on the protesters in Sana in March, killing dozens, their names and hometowns were read out at the central stage at the protest square. Most of them, it turned out, were from Taiz.

It was then that the United States began reconsidering its support for Saleh. He had been an essential if unreliable partner ever since November 2001, when he flew to Washington to pledge his support in the war on terror. Yemen’s role as a wellspring of the global jihad — many of Al Qaeda’s foot soldiers were Yemenis — allowed him to provide intelligence and access to leading jihadi figures like Anwar al-Awlaki, the American-born cleric who is now hiding in the mountains of Shabwa province in central Yemen. Terrorism helped raise the profile of a country that had long been neglected as an arid, impoverished backwater. As one Yemeni official put it to me: “Yemen used to be called the tail of the Saudi cow. Now it is its own cow.”

Yet as American aid and military assistance grew over the years, the diplomats doling it out became increasingly uneasy. Saleh seemed to view Al Qaeda as a bargaining chip, one that could be used to guarantee his own relevance as Yemen’s meager oil and water reserves ran dry. He paroled convicted terrorists, or allowed them to escape from prison, even as he cracked down on peaceful protesters. At the same time, his divide-and-rule policies left him more and more isolated inside Yemen. Eventually, even the Americans and their Saudi partners would turn against him, convinced he was more trouble than he was worth. But the uprising of 2011 took them by surprise, perhaps in part because they (and almost everyone else) underestimated the power of the nonviolent movement that started in Taiz.

Even Yemenis were caught unprepared. Soon after the protests started, sympathy for the baraghala and their cause spread into the most unlikely places. Among the first to embrace it was a paunchy 36-year-old tribesman named Abdullah bin Haddar. Haddar is from Marib, a famously lawless province east of Yemen’s capital. I first met him in the tent where he had been living for four months in the protest square in Sana. I was struck instantly by his appearance: he wore no belt or jambiya, the traditional dagger Yemeni tribesmen always carry on their belts. “I stopped wearing it since I came to the square,” he told me. His head was bare, too — he had disdained the patterned cloths most tribal men wear — and though he spoke in a thick Bedouin accent, he wore rimless glasses that made him look more like an ill-shaved salesman than a feudal warrior.

When the Sana protests first started in February, Haddar told me, he had been at home in Marib, surrounded by his family and a vast armory of weapons. “I used to sleep with guns all around me,” he said. “It always scared my wife.” He needed them. His life, he explained, was dominated and constrained by tribal feuds. The feuds are almost constant in Marib, and because they are collective, any member of the tribe is fair game. Tribal boundaries are closely watched, so that walking or driving into enemy territory can instantly endanger your life. Sana is often just as dangerous, Haddar told me, because your enemies can catch up to you at any time in the anonymity of the crowd, and it is harder to see them coming. “This is why I never learned English,” he said. “The class is always at a certain time and place, so people know where to find you.” Students at Sana University have been gunned down in exactly this way, Haddar and others told me.

Haddar had long nourished a deep hatred for Saleh’s government, which he blamed for much of the misery in Marib. So when the uprising started, he drove straight to Sana and sought out Khaled al-Anisi, a 42-year-old human rights lawyer who had emerged as one of its leaders. When I met with Anisi, he smiled at the memory of the encounter. “Abdullah Haddar told me, ‘I will bring my tribe, we will protect you, we will fight for our dignity,’ ” Anisi said. The uprising was still young, but Anisi, an eloquent critic of the Saleh regime and a pillar of Sana’s small circle of activists, had his priorities set. “The most important thing for us is not getting rid of Ali Abdullah Saleh, or even building a civil state,” Anisi told me. “It is changing the mentality of violence, this culture of the military and of the tribes.” So he offered Haddar a firm rejoinder. “I told him: ‘Thank you, but we don’t want protectors or supporters. We want partners. If we wanted to be safe, we would have stayed home. We hope you will join us.’ ”

That message struck Haddar with the force of revelation. As a tribesman, he had expected his role to be that of hired muscle, an enforcer. “The government has always treated these people as tools,” Anisi told me. “Yes, they give them money and weapons, they talk about dignity, but they never really treat them as equals. They don’t respect them.”

Haddar brought the zeal of a convert to his new role as a protester. “I had never imagined this would be possible, giving up violence,” he said, staring at me with large, earnest eyes. “It is something heavenly, not earthly.” Within days, he had been beaten up badly in a street confrontation with plainclothes government thugs. He wore his new badge proudly, and Al Jazeera broadcast footage showing his bare back covered with scars. Members of his tribe in Marib saw it, and one of them called him right away. “They said we are coming to take revenge,” he told me. “They were heavily armed. I refused. I said if anyone wants to join me, he must leave aside all weapons, and not even carry a dagger. I told them, even if I am killed, they must not retaliate.” This was a violation of one of the fundamental tenets of tribal life. Haddar’s fellow tribesmen, baffled and wondering about his mental health, sent a delegation to see him and explore the sit-in. There were about 25 of them, he said, and on the first day in the city, a group of government thugs recognized Haddar and attacked him. “The tribesmen tried to protect me, but I said: ‘No! Each one protect himself.’ ”

The following weeks were not easy. Haddar got angry calls from family members, who said he was dishonoring them. Government officials sought him out in the square and tried to bribe him away with offers of money and jobs. And he was still frightened of vendettas, even in the protest square. “One man had been trying to kidnap or kill me for two years,” Haddar told me. “I saw him in the middle of Change Square, and I was afraid. But he walked right up to me. He said: ‘Yes, I was planning to kill you. But that’s all over, I’m with the revolution.’ ”

As word spread along tribal networks, more and more men from the provinces came to Sana and other cities to join the protest. Even in provincial capitals, sit-ins were established, sometimes with elaborate deals being struck to suspend feuds so that people could attend without fear of being ambushed. In Sana, tribesmen were invited to sign a document suspending all feuds, I was told by Ahmed al-Zaydi, a 23-year-old activist from Marib. But after Zaydi and other organizers collected hundreds of signatures, the papers turned into a thick, unruly shuffle, and the decision was made to just announce a pan-tribal amnesty on the microphone at the main soundstage at the Sana protest square. Zaydi, a lanky man with long hair and dark skin, now lives in a “tribal tent” in the Sana square with six other young men from Marib, including some with whom his tribe is officially at war. “These feuds are something we learned from the elders,” he told me, as he sat cross-legged at his laptop, drafting a new communiqué. “But enough; we don’t want it. The youth are our only hope for getting out of this cycle of violence.” Zaydi added that there have been no serious fights among tribesmen in the square, while there have been brawls involving members of opposition political parties. “It’s the ones who are supposedly civilized who have had problems,” he said with a smile.

Even as the tribesmen of Marib laid down their weapons, others were planning for war against the regime. In early May, hundreds of armed men began quietly arriving at the ancestral home of the Ahmar family. It is a gated fortress built of gray igneous rock in northern Sana, in a neighborhood called Hasaba. The Ahmars are the leaders of Yemen’s most powerful tribal confederation, known as Hashid, which comprises scores of subtribes and tens of thousands of heavily armed fighters across northern Yemen. Hashid and its largest rival confederation, Bakil, have been known for centuries as the “wings” of the ruler. Although Saleh has done much to divide and co-opt them, the tribes are still a powerful, quasi-independent force in Yemen, whose loyalty is still essential to any government.

Saleh began losing the Ahmars years ago, but the final break began on March 18. On that day, gunmen in plainclothes opened fire on protesters in Sana, killing at least 52 and setting off a wave of defections in the top ranks of Yemen’s government. Sadeq al-Ahmar, the patriarch of the clan, was infuriated by the massacre and announced right away that he was joining the uprising. Sadeq’s brother, Hamidh al-Ahmar, the owner of Yemen’s largest telecom company and a billionaire, had long been one of Saleh’s fiercest critics, and had been providing money and encouragement to the Sana protesters since January. After the massacre in March, both brothers became convinced that only force would rid Yemen of Saleh. For his part, Saleh was certain that the Ahmars had planned the entire uprising, and according to several people who know him, he was bent on taking revenge.

Over the next two months, tensions between the Ahmar and Saleh clans grew worse and worse. The Ahmar mansion in Hasaba is surrounded by government buildings, including the Interior Ministry, and as Saleh began filling those buildings with armed guards and soldiers — on the pretext of preventing a takeover by the Ahmars — the Ahmar clan responded in kind, bringing tribesmen into the city from Amran province to the north, the family’s desert stronghold. The spark came on May 23, after weeks of failed efforts by Arab and American diplomats to persuade Saleh to cede power to a provisional government. It is still not clear who fired the first shot, but within hours, Hasaba turned into a war zone, with heavy artillery crashing around the ancient stone buildings and the chatter of automatic weapons echoing in the narrow alleys. The fighting raged on for two weeks, until the entire area was devoid of people and the streets were littered with rotting corpses. At least 130 people were killed, according to human rights groups, but the death toll may be much higher because the mortar fire was so intense that it was almost impossible to enter the area. The fighting stopped only when a bomb went off in Saleh’s palace mosque on June 3, leaving Saleh with serious burns and splinters lodged in his chest from the mosque’s shattered wooden minbar. The next day, he and at least six other top-ranking government officials were flown to Saudi Arabia for treatment, leaving Yemen in an uneasy political void.

When I met Sadeq al-Ahmar at his family home in Hasaba, the streets nearby still reeked of burned buildings, and I caught a whiff of rotting flesh — human or animal, I could not tell. Ahmar, a short man with creased brows and a hawkish beak of a nose, met me just inside the front gate. He was in full tribal regalia — a gray suit jacket over a light green tunic, a large jambiya sticking out from his belt, and an AK-47 over his shoulder, which he never removed. About two dozen tribesmen followed us as we walked through the compound. The house was in ruins, rubble lying everywhere and black smoke stains covering the walls that were still standing. Ahmar led me to a shattered window surrounded by rubble, its metal grille splayed wide open. “This is where the rocket hit, as we were meeting to make a cease-fire,” he said. “I was behind that pillar.” I peered inside and could see the pillar, alongside mattresses covered with what looked like bloodstains. The rocket had struck as Ahmar was meeting with a delegation that included top government officials. Thirteen people were killed, including prominent tribal leaders. Ahmar led me through to an open-air rotunda made of stone and wood, the only structure that seemed untouched by the fighting, and we sat down, surrounded by his tribal retinue. A camel brayed now and then during our talk, the lone survivor of a herd of 17 that had been living in the compound before the fighting started. The smell of manure drifted over from the pen.

“There is no more government now, just gangs,” Ahmar said. He spoke in a flat, nasal voice, occasionally cracking jokes in colloquial Arabic that sent rounds of laughter through his entourage. We talked briefly about the acting president, Abed Rabbo Mansour Hadi, and Ahmar grinned dismissively, showing a mouth full of worn, brown teeth. The real power in Yemen was Saleh’s family. He ran through a list of them, starting with Saleh’s son Ahmed Ali, who commands the Republican Guard, and his nephews Yahya, Ammar and Tareq, who control other essential security units. “They are just kids; this is the first time they have entered a war,” he concluded. I asked him if the battle with Saleh’s men would resume. He told me it certainly would, unless the acting president was willing to “prove himself a man” and declare a new government, exiling the Saleh sons in the process. He did not need to add that this is profoundly unlikely. The Saleh family still commands support among the tribes on its payroll, Ahmar conceded. I asked if he was he ready for more war. “The fighters are already inside Sana,” he said. “And they are thousands.”

As he ushered me out, Ahmar pointed to a second-floor room in the house, now blackened by fire, its windows smashed. “That is where I used to meet the thief,” he said, meaning Saleh. “He will use everything as a weapon in this fight — Al Qaeda, tribes, anything. I know, I was his friend.” We reached the front gate, and Ahmar pointed up at the portrait of his father. It was untouched by the flames. Alongside it was a huge stone bas-relief of a jambiya, the symbol of tribal honor. “These were the only things that survived,” Ahmar said, giving me a meaningful look. Then he reached out to shake my hand and say goodbye.

Ultimately, the contest between the Ahmar and Saleh clans may come down to cash. Yemen’s tribes are notoriously mercenary, and will fight for whoever pays them. The president and his family have been skimming money from Yemen’s oil business for decades through an elaborate network of middlemen. They have also funneled hefty patronage payments to military and tribal leaders, including, until recently, the Ahmars. Estimates of the Saleh family’s holdings run well into the billions, much of it held overseas. But they have been spending it at a furious rate in the past few months, and not just on fuel subsidies to make up for Yemen’s dire shortage of gasoline. Tens of thousands of tribesmen are paid to show up for weekly pro-government rallies in Sana; reports of their stipends range from 7,000 riyals ($33) to 12,000 ($55) per day. For those not on the payroll, life has gotten measurably worse since the uprising began at the start of the year, with food prices rising fast and water and cooking gas increasingly scarce. If these trends continue, the appeal of hard-line Islamists or other extremists may grow, upsetting all calculations about the loyalty of Yemen’s military or its tribes.

One night in late June, I caught a taxi on a darkened road on the southern edge of Sana. The car was filthy and battered, and the driver, a lanky and talkative young soldier named Abdelaziz who had an ecstatic grin on his face, soon told me he was running out of gas. He pulled over behind a truck on the roadside, where a group of cars were clustered. On the truck were several long-haired young men dressed in rags, unloading yellow plastic jugs of fuel. These were black marketeers, who sell gas for as much as $45 a liter, almost seven times the government-subsidized price at most stations. There, the wait to fill your tank can take days. Abdelaziz pushed to the front and secured a yellow jug in about 10 minutes. He took a length of tubing from his trunk, cut off the end with his jambiya and then, after sticking one end in the jug, sucked on the other end to bring the gas out. It took several tries, and each time he spat out a mouthful of gasoline. He looked up at me, still smiling, and pointed to his mouth, saying, “Got a light?” Finally, we had enough gas to drive on. But after half a mile, his car began to sputter and stall. “There’s water in the gas,” he said. “They diluted it.” We were on a vacant stretch of road, a few hundred yards from the Saleh Mosque, a towering structure that stood illuminated against the city’s darkness. Sana now has only a few hours of electricity a day, but the mosque, built by the president a decade ago, dominates the skyline and is always brilliantly lighted. In the silence, Abdelaziz began telling me about himself. He had been in the army a year, he said, but nowadays his unit was off-duty half the time. His salary was $150 a month, he said, but he had not been paid for months, so his only income came from driving the cab. It was not enough to live on. “I am thinking I will go back to my village, in Dhamar,” he said. “There is no money.” Then, for the first time, he wasn’t smiling. “There is no government,” he said. “There is no state. There is no law.”

One possible future for Yemen is already on display in the country’s far south, where roaming bands of jihadis have taken over large swaths of terrain and the government seems powerless to stop them. When I arrived in Aden, on Yemen’s southern coast, the city was nearly abandoned. The roads were empty. Even the weathered old British expats I met, who have lived in Aden for decades, were joking nervously about escaping on a dhow across the Red Sea to Djibouti. At the hotel where I stayed, an eight-story building with tall iron gates and at least 100 rooms, I saw only three or four other guests. One of them was the governor of Abyan province, just to the northeast, who told me he had been forced to flee to Aden when hundreds of armed jihadis captured his provincial capital, Zinjibar. He was a squat, worried-looking man with a widow’s peak and a thick mustache, and when I said I was a journalist, he looked at me pleadingly, his eyes wide. “They will take over Aden and they will have their own state if there is not immediate international assistance,” he said. There was no air-conditioning in the lobby, and sweat was running down his forehead. A Muzak version of the “Titanic” theme played in the background. I asked him what happened to the Yemeni army. “It was a war,” he said. “The Qaeda people came with a huge number of armed men. There is army there, but they are exhausted from so many attacks. The fighters knew the army’s weak points. Besides, everything is divided now, the government, the army. They took advantage of this.”

I had last visited Aden six months earlier, and the contrast was stunning. At that time, the city was bristling with uniformed security men carrying walkie-talkies, and armored vehicles roamed the streets. The Gulf 20, a regional soccer championship, was taking place. The government was using the event to prove to the world that it could vanquish Al Qaeda, and had flown hundreds of people in from other Arab countries. It claimed to have spent hundreds of millions of dollars — in a country where half the population lives on $2 a day or less — to build a new stadium and refurbish dozens of hotels. The games went off without a hitch, under the watchful eyes of most of Yemen’s active military force.

Now Aden felt like a city under siege. Gunfire echoed as I drove through town, and everywhere I met people who said they feared the city would soon fall. Most of them were uncertain about who these mysterious invaders were. But there were thousands of refugees from Abyan living on the floors of schools and mosques around town, and they had a better idea. One of them, a thin 27-year-old named Majed Salem Saleh, had just returned from a quick visit to his house in Zinjibar earlier that day. He said he was studying engineering but made his living fixing cellphones. “There are some soldiers still on the roads, but they just stand there like pictures, like cartoons,” he told me. “They let anyone through, even Al Qaeda.” As for Zinjibar, it was a ruin, with dead bodies still lying on the streets. The jihadis, who called themselves Ansar al-Shariah, or the supporters of religious law, were in full control. All the residents had fled, except for young men like him, who came and went to make sure their families’ houses were not robbed.

Saleh told me he was amazed by the government’s quick abandonment of his hometown. It took only a few hours, he said, on the morning of May 27. At noon that day, he entered his local mosque for Friday prayers and discovered flocks of foreign fighters, including Egyptians, Sudanese and Iraqis. Their leader was a local man, whom Saleh played soccer with as a boy. After prayers, the commander got up to deliver a speech. “He said, ‘We are here to cleanse the city of infidels,’ ” Saleh told me. “ ‘Anyone who is with the government will be considered an infidel. Today we pray in Zinjibar; next Friday we plan to pray in Aden.’ ” Later that day, Saleh told me, he saw the jihadis open the vault at Zinjibar’s central bank. Saleh watched in amazement as they tossed piles of piles of currency into the air, urging local people to help themselves as the notes fluttered earthward. “They did not steal anything,” Saleh said. “They were the opposite of the Army, which always steals.”

Another Zinjibar man, a somber-faced schoolteacher named Abdullah al-Jifri, was there, too. “There are lots of reasons to join the musulaheen,” he told me. (Like most people, Jifri referred to the invaders as “armed men” rather than jihadis or Al Qaeda, since their affiliations are not always clear.) “First, there is revenge against the security forces for what they have done to us. Second, you might believe in Shariah, as they do. Or you might just be a thug who wants a chance to fight. Or you might join them because you’re a supporter of Ali Abdullah Saleh and you believe that he is secretly backing them.” Jifri was not joking. Most Yemenis are aware that Saleh’s government has collaborated and made deals with jihadis for years. It is not unreasonable to assume that if you pick up a gun and declare yourself an Al Qaeda member, you will be adopted by someone in the military or intelligence, or at least bought off. In Yemen’s disastrous economy, that may be your best job prospect.

Even as the army collapsed in Zinjibar, its commanders tried one last, desperate ploy. They hired a tribal mediator to negotiate a cease-fire. I met him in Aden. He was a 49-year-old sheik named Ali Abdullah Abdulsalam, who prefers to go by the nom de guerre Mullah Zabara. He was an ebullient man with a strong jaw and a scar on his right temple that gave him a fearsome look. He approached me in the lobby of my hotel, and as he kissed my cheeks — the standard Arab greeting for men — I smelled whiskey on his breath. The hotel staff were clearly terrified of him. We sat down, and within minutes he was asking me, with a big devilish grin on his face, how much I would pay for the interview. He said he had information that the C.I.A. would pay a lot of money for. I told him I couldn’t pay anything. He had a sidekick with him, a skinny young tribesman named Taha who sat next to him and soon began whispering, “O.K., that’s enough, drop it.” He dropped it, and then began telling me about his trips to Zinjibar, where he twice met with members of Al Qaeda. After the first trip, he exchanged text messages with a top Qaeda figure named Fahd al-Qusaa, who is wanted by the United States for his role in the U.S.S. Cole bombing in 2000. Al Qaeda leaders never talk on the phone, he explained, because Yemen’s government has voice-recognition software, provided by the United States. (I later confirmed Zabara’s identity and background, and much of his account, through other tribal figures in south Yemen.) He showed me the messages on his phone. They were written in highly formal Arabic and referred briefly to Zabara’s having “protected” Qusaa (if it was him) in the past. The writer of the message expressed his appreciation for Zabara’s mediation efforts but said the government had lied and refused to suspend their fire during the negotiations. “These people cannot be trusted,” the message said. “We will defeat them, and God willing we will conquer Aden.” Zabara told me he refused to give up, and was later granted a meeting with Qusaa’s superiors, whom he named: Said al-Shihri and Qassim al-Raymi, the deputy leader and military commander of Al Qaeda’s Arabian branch. These men were closely involved in the group’s efforts in 2009 and 2010 to set off bombs in airplanes bound for American cities. With Osama bin Laden gone, they are among the top counterterrorism priorities of the United States. Zabara said they were directing the takeover of Zinjibar and other towns, and he had met them in a farmhouse less than an hour’s drive from where we were sitting. His efforts to broker a cease-fire failed.

“If anyone says there is a regime in this country, he lies,” Zabara told me before he left. “We are like Somalia now, but we have yet to start fighting.”

In a sense, south Yemen itself offers a grim cautionary tale about the events now unfolding in Taiz and across the country. Until 1990, when the two Yemens merged, South Yemen was a beacon of development and order. Under the British, who ruled the south as a colony until 1967, and the Socialists, who ran it for two decades afterward, South Yemen had much higher literacy rates than the north. Child marriage and other degrading tribal practices came to an end; women entered the work force, and the full facial veil became a rarity. It was only after Ali Abdullah Saleh imposed his writ that things began to change. When the south dared to rebel against him in 1994, Saleh sent bands of jihadis to punish it. The north began treating the south like a slave state, expropriating vast plots of private and public land for northerners, along with the oil profits. Tribal practices returned. Violent jihadism began to grow.

On my last day in Aden, I went to see an old friend, whose family had left Yemen long before. He had returned now, to help his remaining relatives. We were sitting in a living room with tall windows overlooking the sea. The sound of the surf was audible, and bright red wildflowers trembled in the breeze outside. “This conflict here has become very personal,” he said sadly. “It is all because of the tribal mentality. The youth, with their revolution, were hoping to get past this, to build a civil state. But the military and the tribes are too powerful. Now I think we will have to go through a hell to reach our future. There is no other way.”

In northern Yemen too, along the Saudi border, the government has withdrawn almost completely. Reporters have been unable to visit the far north for years, because of the danger posed by kidnappers and jihadis. But I met tribal leaders from the north who told me the area seems to be turning into a proxy battleground, much as Lebanon did in the 1970s, that could worsen tensions across the Middle East. In the past three months, scores of people have been killed in battles between northern tribesmen allied with Saudi Arabia and a rebel movement that now controls much of the north, and is widely said to be backed by Iran. The Saudis say Iran is financing the rebels — known as the Huthis — so as to create a pressure front against them, much the way Iran uses Hezbollah in Lebanon. In Yemen’s murky landscape, it is difficult to know who is really allied with whom. Iran has long denied that it is meddling in northern Yemen, though high-ranking American officials told me they believe it is true.

One thing seems clear: With the Yemeni government totally absent in the north, the area is a stew of armed groups with no shortage of money or weapons. And the Saudis, who have paid stipends for decades to Yemeni sheiks, appear to be pushing a more sectarian agenda. “The Saudis are now putting strings on the money they give us,” I was told by Abdullah Rashid al-Jumaili, a tribal sheik from Jawf province, in the far north. “They want us to spread the Sunni faith, and to fight the Huthis.” Jumaili, a clean-cut 35-year-old, was open about the support he receives from Saudi Arabia. They give about $2,500 a month, he told me when we met in Sana. But he seemed uneasy about the collapse of any pretense to Yemeni sovereignty over the north. “It seems there is now a struggle between Iran and Saudi Arabia for dominance in northern Yemen,” he said. Partisans of the two sides fought for control of a Yemeni military base between March and June, and at least 70 tribesmen were killed, he said. There is now a cease-fire, but both sides have taken over large stores of weapons from abandoned army bases or bought them on the thriving black market. And both sides, he added, appear to have foreign sponsors with unlimited resources.

Even in Taiz, the heart of the revolution, the protesters are now turning toward violence. One of the city’s leading opposition figures, Sultan al-Samie, commands an anti-government militia. At his base, on a hill overlooking the city, 60 or 70 young men stood guard outside with rifles, hiding among scrubby trees and half-built houses. Samie, a distinguished-looking man of 50 with dark patches under his eyes, is a member of the Yemeni Parliament. He carried a gun during the entire time I stayed with him, and he showed me a little green canvas bag he kept by the stairs, which held a toothbrush, flashlight and change of clothes so that he could move to another location at any time. He has survived several assassination attempts by government security men, Samie told me. He is also a sheik of one of the area’s most prominent tribes. When I asked him about the attack on the square, he began recounting the events of that night, and then broke down momentarily and wept. “We were forced to use weapons. We did not want to, we did not want to.”

Since the attack, opposition tribesmen from villages outside Taiz have taken over large portions of the city, where they man their own checkpoints. At night, Samie took me up to the roof of the house, where there was a view down onto the city. We could not see the protest square, but we could hear grenades and heavy guns being fired down into it from a military base on a hill. “They shoot into the square every night,” Samie said. “It lasts until 2 a.m.” In the other direction, toward the airport, tracers arced across the night sky, as young opposition fighters shot at another military base. I looked down into the trees around the house and saw the guards, clutching their rifles and standing alert by their posts. I asked Samie about several mysterious killings that were reported that day in Taiz, the latest in a series of assassinations. “The first one was an officer killing one of the youth at a checkpoint,” he said. “The officer was then tracked down and killed.” I did not ask him how he knew. The next day, Samie told me about an ambush on a government convoy that had destroyed a large truckload of weapons. When I asked how the attackers had taken the truck out, he said, without hesitation, “It was a rocket-propelled grenade,” and I thought I caught a hint of pride in his voice. “Would you like to see one?” he asked, then went downstairs and came back with the weapon. He then showed me an antitank missile. He was working hard to lure sympathizers inside the military to defect, he told me. The next day, one of his guards drove me past a weapons market at the airport, where I saw row after row of rifles, ammunition boxes and grenades. “The prices are going up,” the guard said. “People did not have weapons before in Taiz. Now everyone is buying them. War is coming.”

On my last day in Taiz, I went once more to see Bushra al-Maqtari in her mother’s house. She showed me her bedroom, the size of a closet, with a small single bed, a tiny wooden writing desk and a dusty shelf packed with novels in Arabic translation. She sleeps in a different place every night now, she said, and is not home as often as she would like. In the living room, I sat with her and her sister and some of their friends. They take an intensively protective attitude toward her, despite her leadership role, perhaps because she suffers from asthma and kidney disease. Her mother brought us tea. Maqtari told me she had been working on a novel when the uprising broke out, and she has been unable to write since then. Through the open window, we could hear the occasional thud of artillery shells exploding somewhere in the distance. “The shelling is every night,” she said. “We can’t demonstrate in peace. There are even women among us who want to bear arms now.” I asked her if she thought the nonviolent ideals of the Yemeni revolution — perhaps the best hope for changing an entire culture organized around violence — would survive. She paused, and her serene face seemed to dip into shadow. “We will always believe it in our hearts,” she said. “But we are all on a thin line now between nonviolence and fighting. I don’t know if it can be maintained.”

Robert F. Worth is a staff writer for the magazine. His last article, about the revolution in Egypt, appeared in May.