The kiang (Equus kiang) is the largest of the Asinus subgenus. It is native to the Tibetan Plateau in Ladakh India, northern Pakistan, Tajikistan, China and northern Nepal. It inhabits montane grasslands and shrublands. Other common names for this species include Tibetan wild ass, khyang and gorkhar.

The kiang is the largest of the wild asses, with an average height at the withers of 140 cm (55 in). They range from 132 to 142 cm (52 to 56 in) high at the withers, with a body 182 to 214 cm (72 to 84 in) long, and a tail of 32 to 45 cm (13 to 18 in). Kiangs have only slight sexual dimorphism, with the males weighing from 350 to 400 kg (770 to 880 lb), while females weigh 250 to 300 kg (550 to 660 lb). They have a large head, with a blunt muzzle and a convex nose. The mane is upright and relatively short. The coat is a rich chestnut colour, darker brown in winter and a sleek reddish brown in late summer, when the animal moults its woolly fur. The summer coat is 1.5 cm (0.6 in) long and the winter coat is double that length. The legs, underparts, end of the muzzle, and the inside of the ears are all white. A broad, dark chocolate-coloured dorsal stripe extends from the mane to the end of the tail, which ends in a tuft of blackish brown hairs.

The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus, via the intermediate form Plesippus. One of the oldest species is Equus simplicidens, described as zebra-like with a donkey-shaped head. The oldest fossil to date is about 3.5 million years old from Idaho, US. The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from western Europe and Russia.

Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus Equus) lived about 5.6 (3.9–7.8) million years ago (Mya). Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a more recent 4.07 Mya for the most recent common ancestor (MRCA) within the range of 4.0 to 4.5 Mya. The oldest divergencies are the Asian hemiones (subgenus E. (Asinus), including the kulan, onager, and kiang), followed by the African zebras (subgenera E. (Dolichohippus), and E. (Hippotigris)). All other modern forms including the domesticated horse (and many fossil Pliocene and Pleistocene forms) belong to the subgenus E. (Equus) which diverged roughly 4.8 (3.2–6.5) Mya.

The kiang is closely related to the onager (Equus hemionus), and in some classifications it is considered a subspecies, E. hemionus kiang. Molecular studies, however, indicate that it is a distinct species. An even closer relative, however, may be the extinct Equus conversidens of Pleistocene America, to which it bears a number of striking similarities; however, such a relationship would require kiangs to have crossed Beringia during the Ice Age, for which little evidence exists. Kiangs can crossbreed with onagers, horses, donkeys, and Burchell's zebras in captivity, although, like mules, the resulting offspring are sterile. Kiangs have never been domesticated.

Three kiang subspecies are currently recognised:

The eastern kiang is the largest subspecies; the southern kiang is the smallest. The western kiang is slightly smaller than the eastern and also has a darker coat. However, no genetic information confirms the validity of the three subspecies, which may simply represent a cline, with gradual variation between the three forms.

The kiang is distributed from the Kunlun Mountains in the north, the Tibetan Plateau to the Himalayas in the south. It occurs mostly in China, but about 2,500–3,000 kiangs are thought to inhabit the Ladakh, Himachal Pradesh, and Uttarakhand regions of India, and smaller numbers along the northern frontier of Nepal.