The document describes early North American societies and complex civilizations that emerged in pre-Columbian Americas. In the central valley of Mexico, the early civilization of Teotihuacan developed between the 1st-6th centuries AD, growing to a large city of 150,000-200,000 people with monumental architecture including pyramids dedicated to gods. Teotihuacan became a center of trade, exchanging goods over a wide network. Later, the Aztecs would come to dominate central Mexico.