Most species only mate with their own kind but situations do occur where hybridisation between species happens naturally. Climate change may cause one species to move into the habitat of another species (e.g. the Grolar or Pizzly bears produced from Polar and Grizzly bear mating's), or availability of same-species mates may require animals to look elsewhere (e.g. Scottish wildcats breeding with domesticated cats).
The genetic identity of the earliest human-made hybrid animals, the kungas of Syro-Mesopotamia published in Science Advances on 14/01/22 show that humans were involved in crossing female donkeys with male hemippes (a Syrian wild ass) to create kungas ~ 4,500 years ago, at least 500 years before horses appeared in the Syro-Mesopotamian region.
The image below, taken from the Standard of Ur in the British Museum shows kungas pulling a wagon into battle.
