The most common theory behind centaurs, and how they first emerged as a type of creature, is pure and simple shock. The idea is that a non-riding culture, or a society of men and women who had never seen horses, or at last never seen men riding them, naturally thought that what they were seeing was one form, –and not two distinct beings. One example of a similar misconception was that reported by Bernal Diaz del Castillo, who claimed that the Aztecs had the same idea the first time they saw men in a Spanish cavalry. Not only that, many non-riding cultures considered horses impossible to tame; they were wild animals, to be hunted, observed, etc., but not trained, or trusted with transportation. The centaur in Greco-Roman mythology would have originated in the Minoan Aegean culture, when it had observed the occasional nomadic tribe on horseback.
The Lapith tribe, in Thessaly, who later were recorded as being cousins, or relations to centaurs in mythology, were said to have been the inventors of horse training, and horseback riding in the region by Greek writers. Thessalians also claimed that their horses in particular were descendants of centaurs. The centaur myth was propagated by invaders from Asia, i.e., Attila, whose mounted archers were infamous for accuracy, as well as fierceness. Pindar was the first classical Greek writer to mention centaurs in his work, though not by name, –earlier writers referred to them otherwise, making their meaning not quite as well understood.
Other theories are that the centaur’s name comes instead from the Greek’s interpretation of the Mesopotamian god, Baal, of fertility, and rain. Baal was horned, and often depicted as piercing the demon Mot, of summer drought with his horns. “Kentauros” meant “piercing bull”, and is in this sense, similar to the Mesopotamian god, though centaurs in Greek mythos were not usually depicted as having horns.