Busy day today, so mostly excerpts from Wikipedia here.
The Míng conquest of Yúnnán was the final phase in the Chinese Míng dynasty expulsion of Mongol Yuán dynasty rule from China in the 1380s. A huge force of 300,000 Hàn Chinese and Huí Muslim troops were dispatched to crush the Yuán remnants in Yúnnán in 1381. After the defeat of the Yuán loyalists (who were also mostly Huí), the Míng Huí remained in Yúnnán as hereditary military colonists. Thousands of te Hàn soldiers also decided to stay in the area. They married local women of Miáo and Yáo descent, and over time began to call themselves Túnbǎo 屯堡, "fortress Chinese", in contrast to newer Hàn Chinese colonists who moved to Yúnnán in later centuries (16th-18th).
Túnbǎo work as farmers and practise their own religion, which is an amalgam of Buddhism, Daoism, and Miáo and Yáo religion (see p30 and 32 of The Celestial Empire). They have their own temples.