Iraq contains the world's richest known archaeological sites of the earliest civilizations of the ancient world dating back more than 5,000 years. The ancient cities of Sumer, Babylon, and Assyria all were located in Mesopotamia. The land of Mesopotamia was lush with vegetation, abundant wildlife, and copious but unpredictable water resources. The Tigris and the Euphrates are at once destructive prone to unpredictable flooding, and productive. Mesopotamia's plentiful water resources and lush river valleys allowed for the production of surplus food that served as the basis for the civilizing trend begun at Sumer and preserved by rulers such as Hammurabi (1792-1750 B.C.), Cyrus (550-530 B.C.), Darius (520-485 B.C.),

Alexander (336-323 B.C.), and the Abbasids (750-1258).