Cyrus the Great, also known as Cyrus II of Persia and Cyrus the Elder, was the founder of the Persian Empire under the Achaemenid dynasty. As leader of the Persian people in Anshan, he conquered the Medes and unified the two separate Iranian kingdoms; as the king of Persia, he reigned over the new empire from 559 BC until his death. The empire expanded under his rule, eventually conquering most of Southwest Asia and much of the Indian frontier to create the largest nation the world had yet seen.