Aztecs: The last Indian empire in the Americas before the Age of Discovery. This civilization existed from 1300 to 1521 AD. They were based in what is now Mexico City. This civilization unified its territory politically after building the city of Tenochtitlan and two other city-states. Their language was Nahuatl or Aztec. The chief of the tribe was the head of the empire who organized the other tribes. An interesting point about them was the growth of commercial behavior and even the formation of cooperative guilds in this field for economic development. Some of the pyramids in these areas, which are made of shell and are older than the Egyptian pyramids, are related to this civilization. The Aztecs also had their own myths and beliefs.