About 750 the city of Cahokia in Illinois expanded with other centres of the “Temple Mound Builders” in the Mississippi Valley.
Mississippian culture reached its peak between 900 and 1250. In what is now Cahokia we found the main ruins of this culture. At its height the population ranged from 10 to 40,000 people spread out over 15 square miles. Cahokia is believed to have been settled by Toltec colonists as early as 600. there are other Mississippian sites in Arkansas and Oklahoma. During 400-year history Cahokia had a trading network extending from Canada to the Gulf of Mexico. They traded mainly copper, obsidian, mica, crystal, gold, silver and conch shells.