Theories about the origins of states and civilizations (for our working purposes the terms are interchangeable) really began with two concepts formulated in the 1920s and 1930s.
The first was the University of Chicago Egyptologist James Breasted's notion of a Fertile Crescent in the Near East. This was a crescent-like zone that extended from the Nile Valley through the Jordan Valley and across into Mesopotamia, a crescent where agriculture, and later civilization, began. This term, little used today, has some general validity, as this was an area of exceptional cultural development some 5,000 years ago.
The second, and more influential, concept was the idea of an Urban Revolution, formulated by V.G.Gordon Childe. Basically, the idea is flawed, for it is too simplistic, and takes little account of environmental factors.
Later theorizing about the origins of states has taken two directions, the one following upon the other. The earlier hypotheses invoked what are often called "prime movers," single causes such as warfare. More recent theories are based on multiple causes, the idea that there was no single, underlying cause of civilization.
Keep the following in perspective as you consider the implications of complex societies.
1. simple cultures were segmented into kin groups that were egalitarian in their relations,
2. simple cultures had an absence of urban agglomeration and formal legal structures, and
3. simple cultures were associated with less population density and were able to exploit a wide range of resources without becoming materialistic.