The Aztec Imperial Period

The Aztec Imperial Period, 1428 to 1521, began when the city-state of Tenochtitlan, together with Texcoco and Tlacopan, formed the Triple Alliance and defeated the dominant regional power Azcapotzalco, launching a century of rapid conquest that brought most of central Mexico under Aztec, or Mexica, tribute and control. Under rulers including Moctezuma I and Ahuitzotl, the empire expanded through a combination of military conquest and a demanding tribute system extracted from subject city-states, wealth that funded the growth of Tenochtitlan itself into one of the largest cities in the world at the time, built on an island in Lake Texcoco and connected to the mainland by causeways, with an estimated population exceeding 200,000. Aztec religious life centered on an elaborate calendar and pantheon and on human sacrifice practiced at a scale and public visibility that shocked and were used to justify later Spanish conquest accounts, most dramatically atop the Great Temple, or Templo Mayor, at the heart of the capital. The empire, weakened by resentment among its many tributary subjects and by smallpox introduced with the Spanish, fell to Hernán Cortés and his indigenous allies with the capture of Tenochtitlan in 1521.