Unicorns are not found in Greek mythology, but rather in accounts of natural history, for Greek writers of natural history were convinced of the reality of the unicorn, which they located in India, a distant and fabulous realm for them. The earliest description is from Ctesias who described them as wild asses, fleet of foot, having a horn a cubit and a half in length and colored white, red and black. Aristotle must be following Ctesias when he mentions two one-horned animals, the oryx (a kind of antelope) and the so-called "Indian ass".