Answer: Cahokia was the largest and most influential urban settlement of the Mississippian culture, which developed advanced societies across much of what is now the central and southeastern United States, beginning more than 1,000 years before European contact. Cahokia was the largest city ever built north of Mexico before Columbus and boasted 120 earthen mounds. ... The city was the center of a trading network linked to other societies over much of North America. Cahokia was, in short, one of the most advanced civilizations in ancient America.
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