An early mention of a creature with features similar to the karkadann is found in On Animals, a work by the Greek grammarian Timotheus of Gaza (5th/6th century), and is echoed in the Kitāb al-Hayawān (“Book of Animals”) by the 9th century Afro-Arab scholar Al-Jahiz.

Abū Rayḥān al-Bīrūnī (Al-Biruni, 973-1048) describes an animal which has “the build of a buffalo…a black, scaly skin; a dewlap hanging down under the skin. It has three yellow hooves on each foot…The tail is not long. The eyes lie low, farther down the cheek than is the case with all other animals. On the top of the nose there is a single horn which is bent upwards.”

A fragment of Al-Biruni preserved in the work of another author adds a few more characteristics: “the horn is conical, bent back towards the head, and longer than a span…the animal’s ears protrude on both sides like those of a donkey, and…its upper lip forms into a finger-shape, like the protrusion on the end of an elephant’s trunk.”

More details on Wikipedia.