Cyrus, or Cyrus the Great, as he's often known, came to power in 559 BC. The throne he inherited was, however, something of a poisoned chalice; there was chronic instability in the kingdom, with warring factions of nobles constantly vying for power. Moreover, the two dominant Iranian tribes—the Medes and the Persians—were deeply antagonistic toward each other. So long as this remained the case, Cyrus's position would never be secure.
Cyrus set about consolidating his power by defeating the lesser Iranian tribes of Asia Minor that had invaded Median territory after the fall of Cyrus's predecessor, his grandfather Asytages. Once Cyrus had successfully conquered Asia Minor, he turned his attention to the Eastern frontiers. There he conquered a succession of Iranian kingdoms, such as Drangiana, Arachosia, Margiana, and Bactria.
Cyrus then headed back west, where he defeated the Babylonians. In doing so, he freed the Jewish people from their Babylonian captivity and instituted the first Charter of Human Rights known to mankind. It was Cyrus's conciliation toward his defeated opponents that gained him the reputation of a wise, benevolent ruler and further consolidated his growing power. Although Cyrus had established a vast empire, he was careful to show respect for the numerous religious beliefs and practices within its extensive borders.