The Achaemenid Empire was an ancient Iranian empire founded by Cyrus the Great of the Achaemenid dynasty in 550 BC. At peak, its territorial extent was roughly 5.5 million square kilometres, making it the largest empire of its time. Based in the Iranian plateau, it stretched from the Balkans and Cyrenaica in the west to the Indus Valley in the east, including Anatolia, Cyprus, Mesopotamia, the Levant, the South Caucasus, parts of Eastern Arabia, and large parts of Central Asia.