"On the western side of the ocean, movements of people and ideas . . . preceded the Atlantic connection. Great empires—in the Valley of Mexico, on the Mississippi River . . . —had collapsed or declined in the centuries before 1492. . . . As Columbus embarked on his first transatlantic voyage, the Mexica, or Aztecs, were consolidating their position [in Mexico]; their city was a center of both trade and military might. Tenochtitlán [the Aztec capital] . . . held 200,000 people, a population greater than in the largest city in contemporary Europe.

". . . The Mississippian culture spread east and west from its center, the city of Cahokia, on the Mississippi River near the site of modern St. Louis. It was a successor to earlier cultures, evidence of which can be seen in the great ceremonial mounds they built. Cahokia declined and was ultimately abandoned completely in the later thirteenth century. . . . Throughout the Southeast, smaller mound-building cente