In preparation, Lee visited the Cahokia Mounds twice and read as much as he could about the succession of conquering tribes ...

Tribes occupied an area reaching from Lake Michicigao (Michigan) to Iowa, Illinois, Missouri, and Arkansas. The five main tribes were the Cahokia, Kaskaskia, Michigamea, Peoria, and Tamaro.

The ancient North American city of Cahokia had as its focal point a feature now known as Monks Mound, a giant earthwork surrounded on its north, south, east and west by large rectangular open areas.