yak, bovine mammal, Bos grunniens, of the Tibet region of China and adjacent areas. It is oxlike in build, with short, thick legs, humped shoulders, large upcurved horns, and a thick coat that hangs down to the ankles. Wild yaks were formerly found from Kashmir to W China, but were so extensively hunted for meat and hides that they now survive only in isolated highlands at elevations above 14,000 ft (4,300 m). They live in herds numbering from 10 to 100 animals, mostly females and young led by a few old bulls; males are mostly solitary. Yaks have been domesticated in Tibet for centuries, and the domestic form has been introduced into other parts of central Asia. The wild yak may attain a shoulder height of 65 in. (165 cm) and have horns 3 ft (90 cm) long; its coat is dark brown. The domesticated yak is smaller, with short horns; its coat, which may be long enough to reach the ground, may be black, brown, reddish, piebald, or albino. Yaks can live on vegetation so sparse that it cannot support other domesticated animals. The domestic yak is a source of milk, butter, meat, hair (for cloth), and leather and is also much used as a beast of burden. Yaks are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Artiodactyla, family Bovidae.