When were the Jews allowed to return from Babylon to rebuild the temple?

Les explains that after Nebuchadnezzar first came in 606 B.C., about seventy years later the Jews were permitted to come back and begin rebuilding the temple. Cyrus made it possible by sending out a decree, and the whole congregation that went back from Babylon numbered 42,360. Even though Jerusalem was then a barren wilderness requiring hard work, it was still home, so they took up the offer to return and rebuild the temple. The context dates this return at about 535/536 B.C.