Strabo Geography 11.5.8

[8] The next peoples to which one comes between Lake Maeotis and the Caspian Sea are nomads, the Nabiani and the Panxani, and then next the tribes of the Siraces and the Aorsi. The Aorsi and the Siraces are thought to be fugitives from the upper tribes of those names ¹ and the Aorsi are more to the north than the Siraces. Now Abeacus, king of the Siraces, sent forth twenty thousand horsemen at the time when Pharnaces held the Bosporus; and Spadines, king of the Aorsi, two hundred thousand; but the upper Aorsi sent a still larger number, for they held dominion over more land, and, one may almost say, ruled over most of the Caspian coast; and consequently they could import on camels the Indian and Babylonian merchandise, receiving it in their turn from the Armenians and the Medes, and also, owing to their wealth, could wear golden ornaments. Now the Aorsi live along the Tanaïs, but the Siraces live along the Achardeüs, which flows from the Caucasus and empties into Lake Maeotis.