Aztec empire

According to Mexica tradition, their wandering ancestors were told by their god Huitzilopochtli to build a city wherever they saw an eagle perched on a cactus eating a snake -- a sign they found on a small island in Lake Texcoco in 1325 CE. That city, Tenochtitlan, grew into one of the largest cities in the world at the time, and the eagle-on-a-cactus symbol still appears on Mexico's flag today. In 1428, Tenochtitlan joined with two neighboring city-states, Texcoco and Tlacopan, to form the Triple Alliance -- what historians usually call the Aztec Empire.

Building a great city on a lake island created a real engineering problem: not enough farmland. The Aztecs solved it with chinampas, artificial "floating gardens" built up from lake mud and vegetation, staked in place and enormously productive. The empire expanded through military conquest, but ruled indirectly -- conquered cities kept their own local rulers as long as they paid tribute (goods and labor) to Tenochtitlan. Aztec religion, like the religions of many ancient civilizations, included multiple gods and required ritual sacrifice, including human sacrifice, which the Aztecs saw as necessary to keep the sun and the world in balance. When the Spanish conquistador Hernan Cortes arrived in 1519, he allied with the Aztecs' rival city-states, and by 1521 Tenochtitlan had fallen -- a conquest you will look at more closely later this year.