At an average altitude of over 4,500 meters, western Tibet's Ngari Prefecture, nicknamed as "the world's rooftop", is a paradise for wild animals to inhabit and reproduce.

 In the mid 1990s, China built the Changtang National Nature Reserve to protect wild animals across the whole Ngari, such as wild Tibetan donkeys, wild yaks and Tibetan antelopes.

Nowadays, more than 40 species of wild animals under first- and second-class state protection inhabit Ngari with the number of wild Tibetan donkeys hitting about 30,000 and that of wild yaks topping about 20,000.