Digging for the Truth2005

Josh Bernstein:
...Native Americans had been building pyramids, or mounds, for thousands of years. One of them, Cahokia, lay at the heart of a metropolis of 50,000 residents. Until its collapse in the 14th century, it was a large empire, as complex as any medieval European city-state. But by the time Hernando de Soto and the Spanish Conquistadors arrived, the power of the Mississippians was greatly reduced.