The Babylonian captivity or exile refers to the time period in Israel’s history when Jews were taken captive by King Nebuchadnezzar II of Babylon. It is an important period of biblical history because both the captivity/exile and the return and restoration of the Jewish nation were fulfillments of Old Testament prophecies.
God used Babylon as His agent of judgment against Israel for their sins of idolatry and rebellion against Him. There were actually several different times during this period (607-586 B.C.) when the Jews were taken captive by Babylon. With each successive rebellion against Babylonian rule, Nebuchadnezzar would lead his armies against Judah until they laid siege to Jerusalem for over a year, killing many people and destroying the Jewish temple, taking captive many thousands of Jews, and leaving Jerusalem in ruins.