Onager of roads, railway lines, and fences required to support mining activities. The Asiatic wild ass is vulnerable to diseases, as well. A disease known as the "South African horse sickness" caused a major decline to the Indian wild ass population in the 1960s. However, the subspecies is no longer under threat to such disease and is continuously increasing in number. 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. The species is legally protected in many of the countries in which it occurs. The
Onager ancestor of all modern equids (members of the genus "Equus") lived around 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 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