The yak (Bos grunniens for the domesticated, Bos mutus for the wild animal – but see below) is a long-haired bovine found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. In addition to a large domestic population, there is a small, vulnerable wild yak population. In the 1990s, a concerted effort was undertaken to help save the wild yak population.
Yaks are heavily built animals with a bulky frame, sturdy legs, and rounded cloven hooves. They are the only wild bovids of this size with extremely dense, long fur that hangs down lower than the belly. Wild yaks are generally dark, blackish to brown, in pelage coloration. However, domestic yaks can be quite variable in color, often having patches of rusty brown and cream. They have small ears and a wide forehead, with smooth horns that are generally dark in colour. In males, the horns sweep out from the sides of the head, and then curve forward; they typically range from 48 to 99 cm (19 to 39 in) in length. The horns of females are smaller, only 27 to 64 cm (11 to 25 in) in length, and have a more upright shape. Both sexes have a short neck with a pronounced hump over the shoulders, although this is larger and more visible in males. Yaks are highly friendly in nature and can easily be trained. There has been very little documented aggression from yaks towards human beings, although mothers can be extremely protective of their young and will bluff charge if they feel threatened