The founder and king of the Achaemenid Empire, the first Persian Empire. In 550 BC, Cyrus the Great led Persian troops to conquer Median kingdom, and built the Achaemenid Empire, the first Persian empire! Persian Empire's conquest began from Lydian Empire. The powerful allied forces were defeated by Persian army, and the Kingdom of Lydia was devastated. After that, Cyrus the Great was still planning a larger expansion. Neo-Babylonian Empire was the next, and Babylon, the grand city near Euphrates, was conquered by Persian forces. The First Persian Empire conquered most of the ancient Middle East and became the largest empire at that time. After taking Babylon, Cyrus the Great called himself "Great king, king of the four corners of the world".