BEIJING — Thousands of Tibetans took to the streets of a city in China’s northwest Qinghai Province on Saturday after the death of a farmer who set himself on fire at a Buddhist religious site, according to Tibetan exile groups. It was the second large protest in Qinghai this week.

The gathering at the Rongwo Gonchen Monastery in Tongren, said to exceed 6,000 people, according to activist groups, was the biggest public protest in China’s traditionally Tibetan areas in recent years and a sign that the spate of self-immolations and demonstrations were spreading beyond the northern wedge of Sichuan Province where most of the unrest — and many of the previous 28 self-immolations — has taken place since last March.

Free Tibet, a group based in London, said it was the most significant act of defiance against the Chinese government since 2008, when rioting in Lhasa, the capital of the Tibet Autonomous Region, shook the Communist Party leadership and prompted a crackdown in the remote high-altitude plateau that is home to five million ethnic Tibetans.

On Friday, at least 1,000 people protested at a government building in Tongde County, not far from Tongren.