Aztecs today live in Mexico City. There are well over 1 million aztecs living here. They are the largest aboriginal group in Mexico. They are mostly illiterate farmers who aren't much like modern Mexicans at all. They still use the Aztec-Nahua language and their religion is a mix of Aztec and Roman Catholicism.
They went to the valley of mexico towards the end of the 12 century. They were poor and have been moving from place to place. There capital Tenochtitlán was founded in 1325. For about a centry they established a freinship with all neighboring tribes. In the 15 century they became a more powerful grop and took over Huastec, Mixtec and Zapotec. They even went as far as Guatamala. Soon most tribes were joining with the spanish to take over the aztecs. It was a very long and hard fought battle. It took a very long time but finnaly the Aztecs were defeated.