ABSTRACT
Introduction The passing of the Classic civilizations was followed by the rise of many new city-states, some of which grew to become impressive empires. The transition began as early as 600 CE in some places. In highland Mexico the Toltec city-state arose first, followed by the Aztec one that grew into an empire. The Aztecs are better known because they survived into the sixteenth century. Their capital was Tenochtitlán, now Mexico City, which began as a pair of small city-states on a swampy island in Lake Texcoco. Aztec religion involved a complex pantheon of deities and frequent human sacrifice. Their calendars were simplified versions of those used earlier by the Classic Maya and other Mesoamericans. The Aztec Empire depended upon elaborate military expeditions, state religion, trade, and tribute, features common to empires everywhere. The empire eventually expanded to both coasts of Mexico, but failed to conquer some obstinate city-states closer to the center. Some of those unconquered enemies joined with Spanish invaders to defeat the armies of Tenochtitlán, and Mexico became a tributary of Spain by 1521.
