When Darius the Mede had extended his empire over the whole of Western Asia and Egypt, he exacted heavy tribute in horses from all subjugated provinces. This was about 520 B.C., and antedated the racing referred to above. In all parts of his extended empire he built roads and established lines of couriers, mounted on fleet horses, that there might be no delay in receiving at his capital and sending out again intelligence of what was transpiring in any part of his dominions. For this service the best and fleetest horses were required, and the only guide we have to determine how these horses were selected we find in the fact that the tribute collected from the little kingdom of Cilicia, formerly a part of Cappadocia, was, in addition to a stated sum of money, one white horse for every day in the year. It is possible that these white Cilician horses may have been the progenitors of the white (grey) race horses spoken of in Media.
In describing the general fruitfulness of Cappadocia, Strabo says: “Cappadocia was also rich in herds and flocks, but more particularly celebrated for its breed of horses.” Strabo speaks of this as a leading characteristic of the country and doubtless it had held pre-eminence in this respect for generations before he wrote. Three hundred and fifty-six years later, when Constantius was selecting his presents of horses for the prince and people of Yemen, in Arabia, he knew just where to look, in all his dominions, for the best of their kind, and selected two hundred “well-bred” ones for Arabia. Sir R. Wilson, in discussing the quality of the Russian cavalry horses about 1810, had evidently heard of this Cappadocian origin of the Arabian horse, but, unfortunately, he got all the parties badly mixed in his reference. He makes Constantine instead of Constantius the donor of three hundred Cappadocian horses, instead of two hundred, and they are given to one of the African princes, instead of to an Arabian prince. The African traveler, Bruce, found some excellent horses in Nubia, Africa, and from their high quality and unusually large size he seems to have jumped to the conclusion that these were the descendants of the three hundred from Constantine.