No one knows for sure who invented horse riding because it happened before written history. The earliest archaeological evidence of horses being used for transport dates from about 2000 B.C.
According to the American Museum of Natural History, wild horses were originally hunted for meat. Evidence from a site in what is now Kazakhstan is some of the earliest evidence of domesticated horses. Archaeologists believe that the people who lived there, known as the Botai, originally started keeping horses for meat and milk but gradually switched to using them for riding and pulling carts. The exact manner in which this occurred is currently unknown. Horseback riding was in use in Iran and Afghanistan before 1500 B.C.