For a long time, the Aztecs were always on the move. No one wanted them as a neighbor. The other tribes kept running them out. The Aztecs had hungry gods. To feed their hungry gods, they captured people and killed them. This was not a happy situation for the other tribes. They did not want the Aztecs living in their area.
The Aztecs had a legend. They believed that one day they would spot an eagle, perched on a cactus, holding a snake. When they saw this, it would be the signal that they had found a place to call home. There, they would settle down forever. Part of the legend was that their gods had told them to settle down peacefully and build a capital city before they did anything else.
That's what they did. One day, a priest saw an eagle, perched on a cactus, holding a snake in its mouth! He could not believe his eyes. He ran back to the Aztec camp to tell his people what he had seen. This happened in the Valley of Mexico, along the swampy shores of Lake Texcoco.
The Aztecs settled down. If you had never heard of the Aztecs, you might think some very clever and peaceful people had moved into your neighbor. You would have been right about the clever. The Aztecs were very clever people.
The first thing the Aztec did was set up a system of free education. Boys and girls and slaves and adults went to school. The Aztecs knew in order to settle down successfully that they would need many engineers and builders and traders.
They adapted to their environment. They built canoes so they could hunt and fish. They created medicines from the many plants they found in the area. They created floating gardens for more places to grow food. They built dikes to hold back water in the swampy areas, to free up land for agriculture and building. They built their beautiful capital city on a swamp, thanks to the skills of their engineers.