Others had preferred to stay among the hills of western Asia and there they had founded the half-independent communities of the Medes and the Persians, two peoples whose names we have copied from the old Greek history-books. In the seventh century before the birth of Christ, the Medes had established a kingdom of their own called Media, but this perished when Cyrus, the chief of a clan known as the Anshan, made himself king of all the Persian tribes and started upon a career of conquest which soon made him and his children the undisputed masters of the whole of western Asia and of Egypt. Indeed, with such energy did these Indo-European Persians push their triumphant campaigns in the west that they soon found themselves in serious difficulties with certain other Indo-European tribes which centuries before had moved into Europe and had taken possession of the Greek peninsula and the islands of the Aegean Sea.