Perhaps most notorious was the irrevocably strict Media-Persian law, which disallowed even the king himself from overturning a given decree. Regarding such a decree which could have cost the Jews their lives, we can read in the book of Esther. Deliverance came that time through Queen Esther's brave and wise actions.
The dream showed that the bear was raised half way up, which probably symbolizes that the government of that kingdom did not attain to the same level of faith in God which Nebuchadnezzar did. Therefore in Nebuchadnezzar's dream of the statue this Media-Persian empire is symbolized by the breast of silver. (See Daniel 2, and illustration 7.10)
King Cyrus, however, was so positive towards his Jewish captives that he freed them, and allowed them to begin to return to their land in order to rebuild Jerusalem and its temple.