CHOSAR, Nepal -- The wind-scoured desert valley here, just south of Tibet, was once a famed transit point for the Tibetan yak caravans laden with salt that lumbered over the icy ramparts of the Himalayas. In the 1960s, it became a base for Tibetan guerrillas trained by the C.I.A. to attack Chinese troops occupying their homeland.
These days, it is the Chinese who are showing up in this far tip of the Buddhist kingdom of Mustang, northwest of Katmandu, Nepal. Chinese officials are seeking to stem the flow of disaffected Tibetans fleeing to Nepal and to enlist the help of the Nepalese authorities in cracking down on the political activities of the 20,000 Tibetans already here.
China is exerting its influence across Nepal in a variety of ways, mostly involving financial incentives. In Mustang, China is providing $50,000 in annual food aid and sending military officials across the border to discuss with local Nepalese what the ceremonial prince of Mustang calls "border security."
Their efforts across the country have borne fruit. The Nepalese police regularly detain Tibetans during anti-China protests in Katmandu, and they have even curbed celebrations of the birthday of the Dalai Lama, the Tibetan spiritual leader, according to Tibetans living in Nepal.
In the first eight months of 2012, the number of Tibetan refugees crossing the Himalayas into Nepal was about 400, half as many as during the same period in 2011. Tibetans blame tighter Chinese security in Tibet, as well as Chinese-trained Nepal border guards, for the reduced migration.
The Nepalese government has also refused to allow 5,000 refugees to leave for the United States, even though the American government has said it would grant the refugees asylum.
"Nepal used to be quite easy for Tibetans, to get jobs here and integrate into the community," Tashi Ganden, a former monk and prominent political prisoner in China, said as he sat on a cafe rooftop in the bustling Tibetan Boudhanath neighborhood of Katmandu. "That was before the Chinese influence."
Nepal is one of the world's most impoverished countries, made poorer by a decade-long civil war between Maoist guerrillas and the military that ended in 2006, and by the continuing instability of the government. The nation is bordered by India and China, and Nepalese leaders have sought to use China as a counterbalance to long-running Indian influence.
The courtship between Nepal and China has gained momentum in recent years, as China has poured in aid money, infrastructure expertise and, in Lumbini, believed to be the birthplace of Buddha, investment in Buddhist sites. Meanwhile, it has been assigning ambassadors to Nepal who have backgrounds in security work.
Former President Jimmy Carter told reporters in Katmandu on April 1 that Chinese pressure was making the journey of Tibetans to Nepal more difficult. "My hope is that the Nepali government will not accede," he said, according to Reuters.
Shankar Prasad Koirala, the joint secretary of the Ministry of Home Affairs, said in a telephone interview that Nepal had not turned its back on the refugees. "The government of Nepal is assisting them and treating them on humanitarian grounds," he said.
Other Nepalese officials have explained that Nepal abides by a "one-China policy" and does not tolerate anti-China separatist activities on its soil.
China's campaign to block Tibetans from entering Nepal increased in 2008 after a widespread Tibetan uprising. Since then, at least 110 self-immolations by Tibetans living under Chinese rule have further prompted Chinese officials to tighten security in Tibetan towns and along the border with Nepal.
The practice of protest by self-immolation has reached Katmandu, making Nepalese officials even more anxious about the Tibetan issue. In February, a Tibetan monk, Drupchen Tsering, 25, died after setting fire to himself near a revered Buddhist stupa, or dome-shaped shrine, in Boudhanath.
Tibetans in the area asked for the monk's body, but local officials had it cremated in the middle of the night late last month, saying no family members had claimed it, and later posted notices warning against public ceremonies, according to the International Campaign for Tibet, an advocacy group based in Washington.
There has been a clampdown on open religious celebrations in recent years, with some Tibetans detained for days. Those celebrations include festivities around the birthday of the Dalai Lama, who lives in exile in India and had a representative in Katmandu until the office was shut down by the government in 2005.
One young man, Tsering, said he went to a monastery in Katmandu in April 2012 for a birthday ceremony, only to find the Nepalese police blocking the area. The gathering was moved to an assembly hall. "We can't even celebrate the Dalai Lama's birthday," he said. "Things have changed a lot."
Mr. Tashi, the former monk, said dozens of Tibetans were pre-emptively detained in January 2012 when Wen Jiabao, the Chinese prime minister at the time, made an unannounced four-hour visit to Katmandu. Mr. Wen had scheduled a visit for the previous month, but it was canceled because of concerns over protests by Tibetans, local residents said. During his visit, Mr. Wen agreed that China would give Nepal $1.18 billion in aid over three years, among other support.
The earliest Tibetan refugees arrived in Nepal in 1959, when the Dalai Lama fled Tibet, and they settled in refugee camps, of which there are still 13. A Tibetan enclave sprang up around Boudhanath. Some Tibetans became rich by making carpets and handicrafts, and prominent Tibetan monasteries amassed wealth and purchased prime real estate in the Katmandu Valley.
The population was bolstered by more recent political refugees, like Mr. Tashi. The Tibetans used to be given refugee cards that guaranteed them some rights, but Nepal ended that practice in 1998.
These days, refugees pay about $5,000 to smugglers to get them to Nepal. They generally stay six to eight weeks at a transit center in the Katmandu Valley run by the United Nations High Commissioner for Refugees, then board a bus for India. There, the Tibetans hope to get an audience with the Dalai Lama.
Some are pilgrims who eventually try to make their way back to Nepal and then Tibet. There is suspicion among longtime refugees that some of the refugees are spies for China.
Before the Tibetan uprising five years ago, 2,000 to 4,000 refugees reached the transit center each year. That dropped to 500 to 600 in 2008, as Chinese security forces locked down Tibetan towns, and crept back up to 850 the next year. It has remained low ever since.
For decades, there had been an understanding that Nepalese border guards would allow refugees they encountered to continue on to sanctuary. But now Tibetans suspect that the low numbers of refugees reaching Katmandu could be in part a result of guards sending back Tibetans they catch, especially since China is now involved in border security training programs.
There is no independent monitoring of the Nepalese security forces on the border. Last year, CNN broadcast video of unknown Chinese men in plain clothes harassing a CNN cameraman on the Nepalese side of the border while a guard stood by.
"We don't really know what happens in border areas now," said Kate Saunders, a researcher for the International Campaign for Tibet.
For China, the Mustang region is one of the most delicate border areas, given the history of the Khampa guerrilla resistance there and the flight through the kingdom in 1999 of the Karmapa Lama, who was secretly escaping to India from Tibet. The border only opens now on rare occasions for a market between Tibetans and local residents.
People of Mustang could once cross into Tibet with a letter from the king to make a pilgrimage to Mount Kailas, the holiest mountain in Tibetan Buddhist cosmology. But the Chinese cut that off a dozen years ago.
"We've asked our government to try to reopen it," said Jigme Singi Palbar Bista, the prince of Mustang. "Our people have always looked to the spiritual light of Tibet."
This article originally appeared in The New York Times.