Ancient empire of Mesopotamia. The name is sometimes given to the whole civilization of S Mesopotamia, including the states established by the city rulers of Lagash, Akkad (or Agade), Uruk, and Ur in the 3d millennium B.C. Historically it is limited to the first dynasty of Babylon established by Hammurabi (1750 B.C.), and to the Neo-Babylonian period after the fall of the Assyrian Empire.