A number of seals seemingly depicting unicorns have been found from the Indus Valley Civilization.Seals with such a design are thought to be a mark of high social rank.These have also been interpreted as representations of aurochs—a type of large wild cattle that formerly inhabited Europe, Asia and North Africa—or derivatives of aurochs, because the animal is always shown in profile, indicating there may have been another horn, which is not seen in profile.

Unicorns are not found in Greek mythology, but rather in the accounts of natural history, for Greek writers of natural history were convinced of the reality of unicorns, which they believed lived in India, a distant and fabulous realm for them. The earliest description is from Ctesias, who in his book Indika ("On India") described them as wild asses, fleet of foot, having a horn a cubit and a half (700 mm, 28 inches) in length, and colored white, red and black.