In 586 BCE, the forces of the Babylonian Empire conquered the Jews, destroying their Temple and carrying off a proportion of the Jewish population into exile.
The captives consisted especially of educated and upper-class people as well as the royal family. This "Babylonian captivity" lasted almost fifty years. In 539 BCE the Persians, under the leadership of the King Cyrus, conquered Babylon, and in 538 Cyrus issued a decree stating that the Jews would be allowed to return to their homeland.
Not only were the Exiles released, but Cyrus, and to some extent his Achaemenid successors, also supported the rebuilding of the Jewish Temple in Jerusalem. Cyrus' policy was motivated not only by his religious tolerance (he also encouraged other, pagan peoples to maintain their own religions) but by statesmanlike wisdom; people treated generously are less likely to rebel.
But not all the Jews wanted to go home. In the years of Exile, the adaptable Jewish people had established themselves in Mesopotamia, settling there and engaging in business and even politics. Many Jews, while remaining devout Jews, did not go back to their homeland. They carried on their lives in their new home, and as the Persian Empire consolidated its rule, some Jews even rose to high positions of service in the imperial court. It...