A member of the subgenus Asinus, the onager was described and given its binomial name by German zoologist Peter Simon Pallas in 1775.

Today, onagers live in deserts and other arid regions of Iran, Kazakhstan, Uzbekistan, Turkmenistan, India, Mongolia and China.

Like many other large grazing animals, the onager's range has contracted greatly under the pressures of poaching and habitat loss.

The onager is a member of the subgenus Asinus, belonging to the genus Equus and is classified under the family Equidae.

The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus via the intermediate form Plesippus.

The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from western Europe and Russia.

[8] Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus Equus) lived around 5.6 (3.9–7.8) million years ago (Mya).

[9] 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)).

[2] During the late Pleistocene era around 40,000 years ago, the Asiatic wild ass ranged widely across Europe and in southwestern to northeastern Asia.

It is the most common subspecies, but its populations have drastically decreased to a few thousand due to years of poaching and habitat loss in East Asia.

Differences in behaviour and social structure likely are the result of changes in climate, vegetation cover, predation, and hunting.

The social behavior of the Asian wild ass can vary widely, depending on different habitats and ranges, and on threats by predators including humans.

Onagers also occasionally form large group associations of 450 to 1,200 individuals, but this usually only occurs in places with food or water sources.

As these larger groups dissolve again within a day, no overarching hierarchy apart from the ranking of the individual herds seems to exist.

Southern populations of onagers in the Middle East and South Asia tend to have a purely territorial life, where areas partly overlap.

The onager is a herbivore and eats grasses, herbs, leaves, fruits, and saline vegetation when available.

[11] The greatest threat facing the onager is poaching for meat and hides, and in some areas for use in traditional medicine.

Habitat loss and fragmentation are also major threats to the onager, a particular concern in Mongolia as a result of the increasingly dense network of roads, railway lines, and fences required to support mining activities.

A disease known as the "South African horse sickness" caused a major decline to the Indian wild ass population in the 1960s.

Various breeding programs have been started for the onager subspecies in captivity and in the wild, which increases their numbers to save the endangered species.

[13] However, close examination of the animals (equids, sheep and cattle) on both sides of the piece indicate that what appears to be a stripe may well be a harness, a trapping, or a joint in the inlay.

But do not laugh at the jackass wild, for there is method in his he-haw: for with maidenly blush, and accent mild, the jenny-ass answers "She-haw".