They don't call it the "Roof of the World" for nothing. Changtang is a giant, high-altitude plateau located in the west of the Tibetan Plateau, which is itself more than 2.5 miles above sea level. So basically Changtang, which has elevations as high as 4 miles above sea level, is the highest part of something that's already really, really tall.
The climate there is extremely cold due to the elevation, but wildlife is plentiful, according to the Wildlife Conservation Society, including chiru, snow leopards, kiang, brown bears, black-necked cranes and wild yaks. Most of it is protected under the Changtang Nature Reserve, the second-largest nature reserve in the world.
Changtang is also home to a few hundred thousand nomads known as Changpa.