Like many other large grazing animals, its range has contracted greatly under the pressures of hunting and habitat loss, and of the six subspecies, one is extinct and two endangered. The Kiang (E. kiang), a Tibetan relative, was previously considered to be a subspecies of the Onager as E. hemionus kiang, but recent molecular studies indicate that it is a distinct species.
Onagers are a little larger than donkeys at about 290 kg and 2.1 metres (head-body length), and are a little more horse-like. They are short-legged compared to horses, and their coloring varies depending on the season. They are generally reddish-brown in color during the summer, becoming yellowish-brown in the winter months. They have a black stripe bordered in white that extends down the middle of the back. They are notoriously untameable. Equids were used in ancient Sumer to pull wagons circa 2600 BC, and then chariots on the Standard of Ur, circa 2000 BC. These have been suggested to represent Onagers, but are now thought to have been domestic asses. (Clutton-Brock)