Cyrus II of Persia, commonly known as Cyrus the Great, was the founder of the Persian Achaemenid Empire. Hailing from Persis, he brought the Achaemenid dynasty to power by defeating the Median Empire and embracing all of the previous civilized states of the ancient Near East, expanding vastly and eventually conquering most of West Asia and much of Central Asia to create what would soon become the largest polity in human history at the time. The Achaemenid Empire's largest territorial extent was achieved under Darius the Great, whose rule stretched from Southeast Europe in the west to the Indus River valley in the east.