Moundville was the best preserved site of its kind in North America and, at its height, the largest and most powerful political and religious center in the Southeast. Native Americans had lived in Alabama for more than 10,000 years, mostly as skilled nomadic hunters and gatherers, but with the rise of large-scale corn agriculture around AD 800, Southeastern Indians began settling in large villages and a rich and complex Mississippian culture arose from the Mississippi River Valley and spread to places such as Moundville. Eight hundred years ago, more than 1,000 people lived there within a mud-plastered wooden wall with guard towers on three sides, while a high bluff on the Black Warrior River formed the northern boundary. Between AD 1200 and 1250, the people of Moundville built at least 29 earthen pyramidal mounds in a roughly rectangular pattern around a large central plaza; ruling families used paired mounds, with a larger one serving as the platform for a noble's residence and a smaller one beside it used for religious rituals. Mississippian society was divided into ranked classes that probably included nobles, warriors, priests, artisans, commoners, and possibly captives. After about AD 1300, only the highest-ranking elites lived at Moundville, but they maintained political and religious control over about 10,000 people along a 60 mile stretch of the Black Warrior River Valley from Tuscaloosa to Demopolis.