The Aztec culture originated in the four-corner area of present day Arizona, New Mexico, Nevada, and Colorado. In the late twelfth century they began a slow migration southward until they reached Mexico and gained prominence in the late fourteen hundreds. The Aztecs were an advanced civilization that built intricate cities such as Tenochtitlan, which was their island capital. The Aztecs were primarily a sedentary culture that relied on hunting and gathering.
According to their own history, when the Mexicas arrived in the Anahuac valley (Valley of Mexico) around Lake Texcoco, the groups living there considered them uncivilized. The Mexicas borrowed much of their culture from the ancient Toltec whom they seem to have at least partially confused with the more ancient civilization of Teotihuacan. To the Mexicas, the Toltecs were the originators of all culture; "Toltecayotl" was a synonym for culture. Mexica legends identify the Toltecs and the cult of Quetzalcoatl with the mythical city of Tollan, which they also identified with the more ancient Teotihuacan.
Sometime during the 12th & 13th century the Aztecs straggled into the Valley of Mexico, led by their chieftain Tenoch. They were a poor, ragged people who survived on vermin, snakes, and stolen food. They were hatred and rejected by all the surrounding inhabitants of the valley, for their barbarous and uncultured habits.
They were driven from one location to another. Early in the 14th century, Huitzilopochtli told Tenoch to lead his people to a place of refuge on a swampy island in Lake Texcoco. When they reached their destination, they were to look for an eagle perched on a cactus, growing from a rock or cave surrounded by water. At that location, they were to build their city and honor Huitzilopochtli with human sacrifices. The city they built was called Tenochtitlan, the city of Tenoch.
Fearless warriors and pragmatic builders, the Aztecs created an empire during the 15th century that was surpassed in size in the Americas only by that of the Incas in Peru. As early texts and modern archaeology continue to reveal, beyond their conquests and many of their religious practices, there were many positive achievements: the formation of a highly specialized and stratified society and an imperial administration, the expansion of a trading network as well as a tribute system, the development and maintenance of a sophisticated agricultural economy, carefully adjusted to the land and the cultivation of an intellectual and religious outlook that held society to be an integral part of the cosmos.