It was a long long time ago during the time when horses first existed. There were two main groups of horses, the ones that lived on high terrains (eg mountains and hills), and the ones that live on normal/ low lying ground. read more
The unicorn was depicted in ancient seals of the Indus Valley Civilization and was mentioned by the ancient Greeks in accounts of natural history by various writers, including Ctesias, Strabo, Pliny the Younger, and Aelian. The Bible also describes an animal, the re'em, which some versions translate as unicorn. read more