This work identifies 'social ideology' as an example of a crucial mover in the emergence of a complex society, and one that helps explain the developments visible in the archaeological record of fourth millennium BC Mesopotamia. It is argued that these developments were the result of an expansion in the exploitation of resources (flora and fauna); acquisition of rare materials, such as stones and metals, probably played a role but not as the primary basis for the resulting pattern. The shape this expansion took was conditioned by a unique ideology, known as 'The Uruk Phenomenon' and the point of departure for this study.