A number of seals seemingly depicting unicorns have been found from the Indus Valley Civilisation.
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.
Cosmas Indicopleustes, a merchant of Alexandria who lived in the 6th century, made a voyage to India and subsequently wrote works on cosmography. He gives a description of a unicorn based on four brass figures in the palace of the King of Ethiopia. He states, from report, that “it is impossible to take this ferocious beast alive; and that all its strength lies in its horn. When it finds itself pursued and in danger of capture, it throws itself from a precipice, and turns so aptly in falling, that it receives all the shock upon the horn, and so escapes safe and sound”.
Medieval knowledge of the fabulous beast stemmed from biblical and ancient sources, and the creature was variously represented as a kind of wild ass, goat, or horse.
The Throne Chair of Denmark is made of “unicorn horns” – almost certainly narwhal tusks. The same material was used for ceremonial cups because the unicorn’s horn continued to be believed to neutralize poison, following classical authors.