The Median Empire was then conquered by Cyrus in 547 BC, under the Achaemenid dynasty, and the Persian Empire was thus founded, which consumed the entire Neo-Babylonian or "Chaldean" Empire in 539 BC. King Cyrus changed Assyria's capital from Nineveh to Arbela. Assyrians became front line soldiers for the Persian empire under King Xerxes, playing a major role in the Battle of Marathon under King Darius I in 490 BC. Cyrus II returned the sacred images of the Assyrians to Nineveh and Assur, established for them permanent sanctuaries, gathered all their former inhabitants and returned them to their habitations. At the news of the assassination of Bardiya (son of Cyrus II), and this connection, Darius the Great declared that several satrapies including the Assyrian satrapy revolted. In 482 BC, Babylonia and Assyria were joined together in the same administrative division.