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.