From time to time one of the tribes into which that mountainous country was divided obtained supremacy over the rest: at first the Athenians, owing to the prominent part they had taken in repelling the Persians; then the Spartans, and finally the Thebans.

But on the northern frontiers a race of hardy mountaineers, the Macedonians, had consolidated their power, and, under Philip of Macedon, became masters of all Greece.

Philip had learned the lesson taught by the successful retreat of the ten thousand, and, just before his death, was preparing to attack the Great King (of Persia) with all the forces which his supremacy in Greece put at his disposal.

His son Alexander the Great carried out Philip's intentions.

Within twelve years (334-323 B.C.) he had conquered Persia, Parthia, India (in the strict sense, _i.e._ the valley of the Indus), and Egypt.