Like all empires it was founded on the ruins of others but, unlike those that had preceded it, instead of remaining confined within the territorial limits of the Near East the Persian Empire was still expanding. From 547 B.C. onwards it continued to do so for some seventy years. Its first real check was in Greece, but despite even this it was not until the campaigns of Alexander the Great that its power was finally broken. Even then, when Alexander’s empire splintered after his death, the world and culture of Iran, in the shape of the new Persian Empire, revived and continued the later struggle against Rome. It did not finally collapse until the seventh century when the Arabs, always unconquered, overthrew it. For over a thousand years, the East challenged the West, and the most crucial of all these challenges was that which was now set in motion by Xerxes. Had it succeeded, the Zoroastrian creed might have been imposed upon the pagan Greeks. There would have been no fifth-century Athens, and all European history would have been very different.
