Ancient History/Americas/Aztec Empire/Origins of the Aztec
The Aztecs were from a place called atzlan which is where the term Aztec derives form, ironically enough they swore they would never be called by this name again upon leaving and preferred the term Mexica which is where the name of the country Mexico derives from
Atzlan is Nahuatl for place of the heron which was an island whose location is disputed due to the fact that only the aztecs lived there and hadn't for 100's of years when the first Europeans arrived. They got to that island through 7 caves which the culture of the island had been living in supposedly since humanity began, which is either off the coast of northwestern Mexico or somewhere else. Some people have said it's as far as Wisconsin while others claim it was a town now called Aztlan, and others say it's a mythical place and the whole story is made up.
The 7 Tribes
The 7 Tribes each originating from 1 of the caves agreed to leave atzlan in hopes of building a new city that they could live in. It would be called Tenochtitlan which is aztec for Cactus Rock. Their god had told them to look for it as "A place where there is a cactus growing from a rock with an eagle perched on it with a snake in it's mouth". He had said to settle in the place where they found it when they began their journey South or possibly Southwest to what today is Central Mexico.
The Aztecs went south through Mexico toward Tenochtitlan. Not yet knowing where that was they went south looking for the sign their god had told them about. The people of Mexico called the Toltecs, who had been around for a very long time and were similar to the Maya, these peoples land was now being entered by stray tribes such as the Aztecs but by the time they got there, most of the land in the area had already been taken They were influenced by Toltec Culture and added some of their gods to their religion (later a fatal mistake). They were accepted into one society who they angered when they sacrificed a woman they gave them, who they expected their ruler to marry. Then they banished the Aztec into the lake. They went through lake Texcoco and found the sign, there they settled.