All had worn the crimson robes of Kirti Monastery, a venerable institution of learning ringed by mountains on the eastern edge of the Tibetan plateau. All set themselves on fire to protest Chinese rule. Two died.

At least 38 Tibetans have set fire to themselves since 2009, and 29 have died, according to the International Campaign for Tibet, an advocacy group in Washington. The 2,000 or so monks of Kirti Monastery in Sichuan Province have been at the center of the movement, one of the biggest waves of self-immolations in modern history. The acts evoke the self-immolations in the early 1960s by Buddhist monks in South Vietnam to protest the corrupt government in Saigon.

Twenty-five of the self-immolators came from Ngaba, the county that includes Kirti; 15 were young monks or former monks from Kirti, and two were nuns from Mame Dechen Chokorling Nunnery.

Chinese paramilitary units are now posted on every block of the town of Ngaba, and Kirti is under lockdown. Journalists are barred from entering the monastery, which has made the question of how Kirti became the volcanic heart of this eruption of self-immolations something of a mystery.

But monks and laypeople from Ngaba who have fled across the Himalayas to this Indian hill town said that Kirti had been radicalized in the last four years by an occupation of the monastery that amounted to one of the harshest crackdowns in Tibet. Chinese security measures have converted the white-walled monastery, with its temples and dormitories and rows of prayer wheels, into a de facto prison, which has fueled the anger that the measures are aimed at containing.

After a five-week lull, the self-immolations picked up again last week. On May 27, two men in Lhasa, the Tibetan capital, set fire to themselves outside the Jokhang Temple, the holiest in Tibetan Buddhism. It was the first notable act of protest in Lhasa in four years. One of the men was a former Kirti monk.

On Wednesday, a mother of three burned herself to death in Ngaba, known as Aba in Chinese.

The Ngaba exiles here say the security measures imposed on the town and the monastery have been extreme, even by the standards of Chinese control in Tibet. In 2008, during a Tibet-wide uprising, security forces shot protesters in Ngaba with live ammunition, killing at least 10 civilians, including one monk, according to reports by advocacy groups and photographs of corpses that had been brought to Kirti. It was one of the most violent events of the uprising, and anger and alienation set in among local Tibetans. Officials tightened security.

In February 2009, in the town's market area, a young man from Kirti self-immolated, the first monk to do so in modern Tibetan history. The monk, named Tapey, survived, and officials stepped up surveillance of Kirti. In March 2011, the next self-immolation occurred: Phuntsog, 20, set fire to himself on the same street in the market, which locals now call Hero's Road.

Local Tibetans say the heavy-handed reaction of the authorities in the six months after that event backfired, encouraging the self-immolations to continue. Chinese officials ordered the People's Armed Police to surround the monastery; built a wall to cut off a rear entrance; banned all religious activities; smashed photographs of the Dalai Lama, the Tibetan spiritual leader; forced monks to attend patriotic re-education sessions; cut off Internet access; and barred pilgrims from entering. They also took away 300 monks in a nighttime raid; many of them have not returned.

Kanyag Tsering, a Kirti monk in exile who keeps in touch with colleagues in Ngaba, said about 300 officials now lived inside the monastery to keep watch. Last summer, at the height of the patriotic re-education campaign, there were perhaps twice that many.

Another Kirti monk, Lobsang, said the paramilitary police had set up four camps around the monastery.

"The most uncomfortable thing was seeing soldiers pointing guns at you but not shooting at you," said Lobsang, who recently arrived here and agreed to speak on the condition that only his first name be used. "This has been daily life since 2008. For myself, I'd rather get shot than to have them pointing the guns at me every day, 24 hours a day."

He said there did not appear to be any coordination or organized plan for self-immolation.

"I think those who self-immolated didn't have an official agreement, but there was spiritual solidarity between people," he said. "The energy of the Tibetan people is totally linked like a bracelet of prayer beads. You cannot find the end and the beginning because it's a circle."

Chinese officials have condemned some of the self-immolators as "terrorists" and blamed the Dalai Lama for inciting the acts, a charge he has denied.

Researchers for Human Rights Watch attribute much of the frustration in Ngaba to the smothering security and "provocative policing techniques." The group found that per capita government spending on security in Ngaba from 2002 to 2006 was three times the average for non-Tibetan parts of Sichuan. There was a rapid increase after 2006, and by 2009 it was five times that of non-Tibetan areas.

Top officials have signaled their approval of the security clampdown. In February, the party chief of Ngaba, Shi Jun, was promoted to lead Sichuan's public security bureau.
A former monk with whom Lobsang had close ties, Rinzen Dorje, was one of those who felt suffocated by the security. He left Kirti Monastery in 2010 to herd animals and do manual labor. He set fire to himself at a primary school one evening in February. Lobsang last saw him in July.

"He told me he felt very uncomfortable and had headaches when he saw the atmosphere in Ngaba town," Lobsang said.

That was also the case with Tapey, the first monk to self-immolate, Lobsang said. Two days before his self-immolation in 2009, Tapey was walking among military trucks and kicking them.

"He was intentionally trying to provoke the soldiers," Lobsang said. "I asked myself, 'What happened? What's wrong with him?' That day he was really different, and in his eyes I could see how he hated the military."

On Feb. 27, 2009, a high lama told a gathering of monks that Kirti had to comply with official orders to cancel an important prayer ceremony scheduled for that day. Tapey set himself on fire in the marketplace half an hour later, having left a note saying he would kill himself if the government banned the ceremony, Lobsang said.
"The people very much respected his motivation and the price he paid for freedom," Lobsang said.

The next monk to self-immolate, Phuntsog, never appeared to be in a dark mood, said Lobsang, who had studied with him. Phunstog liked to joke and play around with friends, often showing off his biceps by flexing.

"I never heard any political agenda expressed by Phuntsog," Lobsang said. "The action he took is unimaginable to me. But, of course, we can now understand how many things he must have hid inside."

After that self-immolation, the authorities started an intense re-education campaign and locked down the monastery for half a year. That led to the radicalization of more monks. One of the tensest moments came in April 2011, when officials sought to detain monks who were not from Ngaba. Residents of the town tried to block the police, and two elderly Tibetans were beaten to death, according to the International Campaign for Tibet. Officers took away 300 monks.

In August, a court sentenced three monks to more than a decade in prison, two of them for being involved in Phuntsog's self-immolation and one, an uncle of Phuntsog's, for refusing to turn his body over to the police at the time.

One day in September, after officials had eased some restrictions on Kirti, two monks raced through the marketplace at noon, their robes aflame. One held up the banned Tibetan snow lion flag. Before collapsing, one of the monks, Lobsang Kelsang, a younger brother of Phuntsog's, shouted, "We are the accused."

The event was described by a witness who arrived in Dharamsala this spring. "Because of unfair judgments, oppressive policies and discrimination, because of all those things, the Tibetan people feel isolated," he said. "The self-immolations are not the end. This is only the beginning."