Ten tons of animal bones. 99.9 per cent of which were equine

Certainly by the fourth millenium BCE: remains found in a northern Kazakh burial site from that period contained ten tons of animal bones. 99.9 per cent of which were equine. Many of the jaws and teeth show the sort of wear you would see on a horse fitted with a bit, which suggests that steppe people were riding horses about 5,000 years ago at a time when the first pharoah was unifying the upper and lower lands of Egypt, when Gilgamesh built the incomparable walls of Uruk, Aborigines were engraving rocks around what is now Sydney, settlements began to appear in Central America and the Cycladic civilisation emerged in Greece.  

A. Sattin, Nomads (2022), 48-9