They came to the Valley of Mexico named Anahuac, (2) led by their chieftain Tenoch. They were a poor, ragged people who ate  rats, snakes, and stole food.

They were just too wild and nasty. So they were driven from one place to another.

Then Tenoch had a vision ... Huitzilopochtli told him to lead his people to a  swampy island in the middle of Lake Texcoco. He was told to look for an eagle perched on a cactus, growing from a rock or cave surrounded by water. They were to build their city  there and thank  Huitzilopochtli for his brilliant idea with human sacrifices. The city they built was called Tenochtitlán, the city of Tenoch in around 1325.

It was very hard to build Tenochtitlan because the Aztecs only had a small piece of land in the surrounding marshes.

The Aztecs made the swampy, shallow lake into chinampas. They made  islands by piling up mud from the lake bottom. They used them as their city foundations. To start with they built a few thatched, mud huts, and some small temples.

Then they built causeways and bridges to connect the city to the mainland. They dug canals and lined them with stone so that people could move easily around.

The city and the Aztecs were all powerful... an EMPIRE.

By 1519 there were about 60,000 people in the city every day.