The Collapse of Civilization in Southern Mesopotamia

In the late ninth century, rural settlement, agriculture, and urbanization all collapsed in southern Mesopotamia. We first document this collapse using newly digitized archaeological data. We then present a model of hydraulic society that highlights the collapse of state capacity as a proximate cause of the collapse of the economy and a shortened horizon of the ruler as a potential driver of the timing of the collapse. Using cross sections of tax collection data for 27 districts in southern Mesopotamia in 812, 846, and 918, we verify that the proximate cause of the crisis was the collapse in state capacity, which meant that the state no longer maintained the irrigation system. A particularly destructive succession struggle, shortening the investment horizon of rulers, determined the timing of the crisis.