The Persian Empire was the world's first hyperpower, with territory stretching from Central Asia to Northeastern Africa and from Southeastern Europe to the Indus Valley. It was the dominant geopolitical force from the later sixth century to its conquest by Alexander in the 330s BCE. Much of the empire's territory was conquered by its founder, Cyrus the Great, who reigned from 559-530 BCE. Cyrus became a legend in his own lifetime, and his career inspired keen interest from Persia's unruly neighbors to the west, the ancient Greeks. The idealized portrait of Cyrus by the Greek Xenophon had a profound impact on ancient, medieval, and early modern debates about rulership. The Persian Empire was the world's first hyperpower, with territory stretching from Central Asia to Northeastern Africa and from Southeastern Europe to the Indus Valley. It was the dominant geopolitical force from the later sixth century to its conquest by Alexander in the 330s BCE. Much of the empire's territory was conquered by its founder, Cyrus the Great, who reigned from 559-530 BCE. Cyrus became a legend in his own lifetime, and his career inspired keen interest from Persia's unruly neighbors to the west, the ancient Greeks. The idealized portrait of Cyrus by the Greek Xenophon had a profound impact on ancient, medieval, and early modern debates about rulership.