The Yak, once found from Kashmir to China can now only be found wild in isolated highlands at elevations of above 14,000 feet due to them being extensively hunted for meat and hides. Wild herds range in size from 10 to 100 animals and consist of females and young, led by a few older males, with breeding males being mostly solitary.

Yaks have been domesticated in Tibet for centuries, and from there were introduced into the rest of China.  Domesticated Yaks are smaller than the wild ones, and come in a variety of colors, including:  black, brown, reddish, piebald, and albino.  Yaks can live on vegetation that is too sparse to sustain other forms of domesticated animals.  The domestic Yak is an incredibly important part of Tibetan life and provides a source of milk, butter, meat, hair ( for cloth ), and leather and is also much used as a beast of burden. 

www.schreinerfarms.com/yak.htm

The chiru is endemic to the Tibetan Plateau. It weighs 26 - 40 kg (57 - 88 lb) and favors alpine steppe or similar semiarid habitats. The chiru prefers flat to rolling terrain, although it readily ascends high rounded hills and penetrates mountains and crosses passes by following valleys. It can be found at elevations from 3250 - 5500 m (10,660 - 18,000 ft). Movement patterns of the chiru are complex, with females following different patterns from males.  Females can migrate up to 300 km (190 mi) between winter mating grounds and summer calving grounds. Chiru herds also vary widely in size and composition. Although herds of 15,000 are no longer seen, as they were a century ago, herds of 1000 or more can still be observed.

The chiru is found primarily on the alpine steppe of northwest Tibet in China. There are a number of both migratory as well as resident populations. The only chirus found outside China are in the Ladakh area of India and comprise only about 200 animals. From Ladakh, the chiru's distribution extends 1600 km (990 mi) eastward across Tibet and southern Xinjiang to Qinghai. The range of the chiru from west to east appears to be much as it was a century ago. However, the range has contracted in central Tibet and eastern Qinghai.

Poaching is the most serious threat to the chiru. It is being slaughtered illegally by the thousands for its wool, which is known in the international market as "shahtoosh" or "king of wool."

Animals of Tibetan Nomads

From The Conservancy for Tibetan Art and Culture
http://www.tibetanculture.org/index.htm

Tibetan nomads raise yaks, yak-cattle hybrids (dzo), sheep, goats, and horses. The rugged land and harsh climate of the Himalayas and Tibetan rangeland require the seasonal movement of these animals between lowland and upland pastures. This pastoral cycle continues today with the movement of millions of animals. These animals provide milk and milk products, meat, hair and wool, and hides for the nomads' basic existence. Yaks are unique to the Tibetan region and make life possible for people across much of Tibet. Their domestication perhaps 4,000 years ago enabled nomads to populate the Tibetan steppe. These animals can withstand colder temperatures than horses and can travel across rough terrain easily. Yaks have been crossbred with cattle so that they will produce more milk and calves. Yaks' long, coarse hair is woven into strong nomadic tents that keep out the rain and fierce winds, yet let light in. Tibetans place so much value on the yak that the Tibetan term for yaks, nor, can be translated as "wealth." Yaks are trained to the saddle and are used as pack animals and mounts. Some yaks are now raised in the western United States.

Sheep provide greater income for nomads than yaks due to the value of their wool. Nomads eat their meat and trade it to settled farmers. Tibetan sheep wool ranks among the highest in quality for carpet production due to its elasticity and deep luster. Tibetan goats are raised primarily in western Tibet. Nomads barter the goats' milk and meat for staples. These animals also produce the fine cashmere wool famous for centuries in shawl production. "Cashmere" got its name from the region of Kashmir presently in India and Pakistan, where the fabric was traded. The reputation of this wool remains strong today through the production of pashmina shawls, a product of the finest goat wool. The controversial shatoosh shawls, appropriately banned in India and the West, are made from the neck hair of the endangered wild Tibetan antelope.