The Greeks call the red and black inhabitants of the land of the south, Ethiopians. According to the statements of Artemidorus of Ephesus and of Agatharchides, which have been preserved by Strabo and Diodorus, the land of the elephant-hunters and ostrich-eaters, who fought with the Ethiopians, men armed with the horns of the antelope, began south of the confluence of the Atbara and Bahr-el-Azrek or Blue River, and the Nile.[169] At the present time the region of the ebony-woods and elephants begins in the marsh at the foot of the Abyssinian Alps; elephants are not found elsewhere except in some more northern regions on the Red Sea; and that the Ethiopians did not acquire the elephants' tusks in the way of trade is proved by the small amount of gold which they had to pay as tribute. As we find in the reliefs of Persepolis and Naksh-i-Rustem, among the nations of the Persian kingdom, certain figures which are marked out as negroes by their short, curly hair, their snub nose, their bare breast and the animal's skin on the shoulders; as the Ethiopians of Nysa and their neighbours served, according to Herodotus, in the army of Xerxes, and paid the tribute mentioned, as Herodotus expressly tells us, even in his day, the march of Cambyses must have penetrated beyond the mouth of the Atbara, and Napata must have been permanently maintained, otherwise such distant tribes would not have furnished contingents in war fifty years later, and their tribute would have come to an end long before Herodotus.