Living in the Dulong River valleys, the Derung people are known for their tradition of facial tattooing adult women. Cheng Bin / For China Daily

Without the Derung people's protection and sacrifice, the Dulong River valleys would not harbor one of the country's best preserved primitive forests, Li Haishu, director of the forestry bureau of Nujiang prefecture inYunnanprovince, tells China Daily. 

"As a treasure trove of biodiversity, the area is considered one of the country's last virgin lands of discovery," he says.

According to the official who has been working in nature conservation in the region for a dozen years, only about 3,000 Derung people live at the Dulongjiang township in Gongshan county, with an area of 1,900 square kilometers, of which 242,800 hectares belong to the Gaoligong Mountains National Nature Reserve.

Covering an area of 405,200 hectares, the reserve is the largest in the province and home to 4,300 species of seed plants and 116 species of mammals, including 11 species of primates.

"Of China's 26 primate species, we have 11," the director says. "The Gaoligong Mountains are the only places on the earth where you can find two of the world's five snub-nosed monkeys. It truly reveals our ecosystem's uniqueness and richness in terms of biodiversity."

But the reserve's patrol station in Dulongjiang township has only five full-time employees and no frontier guards are stationed there.

"The Derung people are truly the main force of protection in the area," he says.