In about BC 580, everyone's favorite
Babylonian,
Nebuchadnezzar, conquered the
Southern Kingdom (which was the Kingdom of
Judah) and took all of the
Jews therein as captives. He shipped them all to
Persia, where they served as slaves. The
Babylonians were actually fairly kind enslavers in that they allowed the
Jews to publicly keep their old
religion, rather than forcing a new one on them.
In
Babylonia, they encountered
Zoroastrianism and wound up incorporating it into their thought. It has
had quite a bit of influence on
Jewish and thus
Christian theology. Before the
Jews encountered it, there really was no "adversary" as it were;
devils,
demons,
hell, and so forth were not believed in. In addition, "
heavenly" entities like
angels were also not thought to be. Basically, they thought that the only big, supernatural entity floating around was
Adonai, and that was that.
The
Jews were kept in captivity for about 70 years, at which point
Cyrus, the king of
Babylonia of the time, released them from servitude, allowing them, if they wished, to return to
Israel.
The Babylonian Captivity was a major milestone for the
Jewish peoples, and is referred to as the
exile (not to be confused with their exile at the hands of the
Egyptians or
Israel's exile at the hands of the
Assyrians).