The population of ancient Mesopotamian cities 2300 BCE Uruk had a population of 50,000 while Mari, to the north, had 10,000 and Akkad 36,000 (Modelski, 6). The populations of these cities were divided into social classes which, like societies in every civilization throughout history, were hierarchical. These classes were: The King and Nobility, The Priests and Priestesses, The Upper Class, the Lower Class, and The Slaves.