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.