in 539 BC, an alliance of Persians and Medes, put together by Cyrus the Great, founder of the Achaemenid (greater Persian) empire, conquered the Babylonians. Besides being a Zoroastrian, Cyrus was very tolerant of other religions and had no desire to keep the Jews captive. In 538 they were released (though many refused to go, Babylon remaining a centre of Jewish culture for a millennium and a half).8
