So Aztec religion held that history was cyclical and punctuated by terrible disasters and then would ultimately end with a massive apocalypse. And the job of the priests was to avoid these disasters by appeasing the gods, generally through human sacrifice. The Aztecs extended their control over most of southern Mexico, parts of Guatemala and the Yucatan, and they demanded tribute from conquered people in the form of goods, precious metals, and people to sacrifice. If you're familiar with The Hunger Games, it won't surprise you to learn that this didn't sit very well with said conquered people. And the fact that the Aztecs were basically ruling over thousands of people who hated them made it a lot easier for Cortes to come in and find allies to overthrow them. All that noted, in less than 100 years, the Aztecs accomplished some amazing things. Especially the building of their capital city Tenochtitlan on the site of modern-day Mexico City, which was like Venice in that it was divided and serviced by canals.