Cyrus the Great (ca.600 - 529 BCE) was a towering figure in the history of mankind. As the "father of the Iranian nation", he was the first world leader to be referred to as "The Great". Cyrus founded the first world empire - and the second Iranian dynastic empire (the Achaemenids) - after defeating the Median dynasty and uniting the Medes with the other major Iranian tribe, the Persians.