 It is generally believed that most Tibetan ponies descended from ancient stock, likely partly from the Mongolian Pony and Chinese breeds.However, some breeds, such as the Nangchen horse have apparently have been bred pure for centuries.Another type, the Riwoche horse, has been hypothesized to have been developed in isolation to a degree that some claim it is an evolutionary link between the prehistoric wild horse and the modern domestic horse, though it could also be a domesticated variety that reverted to primitive coloring.