Media means in the bible: It lies between Elam and the Caspian Sea, and is bordered by Mount Zagros to the west and Parthia to the east. At one point, it was a tributary region of the Assyrian Imperial. However, the Assurbanipal reign 666-624 B.C. saw the country shake off its yoke and Cyaxares, the Median king, joined Nabopolassar, the Babylonian King, in overthrowing Nineveh. Cyrus won Media by defeating the Astyages in 550 B.C. He then united it with the Persian kingdom.
(in Bible Dictionary)