Strabo Geography 3.4.15

[15] All the Iberians, so to speak, were peltastae, furnished with light arms for the purposes of robbery, and, as we described the Lusitanians, using the javelin, the sling, and the sword. They have some cavalry interspersed amongst the foot-soldiers, the horses are trained to traverse the mountains, and to sink down on their knees at the word of command, in case of necessity. Iberia produces abundance of antelopes and wild horses. In many places the lakes are stocked. They have fowl, swans, and birds of similar kind, and vast numbers of bustards. Beavers are found in the rivers, but the castor does not possess the same virtue as that from the Euxine, ¹ the drug from that place having peculiar properties of its own, as is the case in many other instances. Thus Posidonius tells us that the Cyprian copper alone produces the cadmian stone, copperas-water, and oxide of copper. He likewise informs us of the singular fact, that in Iberia the crows are not black; and that the horses of Keltiberia which are spotted, lose that colour when they pass into Ulterior Iberia. He compares them to the Parthian horses, for indeed they are superior to all other breeds, both in fleetness and their ease in speedy travelling.