Aztecs are the collective name given to seven Chichimec tribes of northern Mexico, who controlled the valley of Mexico and much of central America from its capital during the Late Postclassic period from the 12th century AD until the Spanish invasion of the 15th century. The main political alliance creating the Aztec empire was called the Triple Alliance, including the Mexica of Tenochtitlan, the Acolhua of Texcoco, and the Tepaneca of Tlacopan; together they dominated most of Mexico between 1430 and 1521 AD.
For a complete discussion see the Aztec Study Guide.
Aztecs and their Capital City
The capital city of the Aztecs was at Tenochtitlan-Tlatlelco, what is today Mexico City, and the extent of their empire covered almost all of what is today Mexico. At the time of Spanish conquest, the capital was a cosmopolitan city, with people from all over Mexico. The state language was Nahuatl and written documentation was kept on bark cloth manuscripts (most of which were destroyed by the Spanish). Those that survive, called codexes or codices (singular codex), can be found in some small cities in Mexico but also in museums around the world.
A high level of stratification in Tenochtitlan included rulers, and a noble and commoner class. There were were frequent ritual human sacrifices (including cannibalism to some degree), part of the military and ritual activities of the Aztec people, although it is possible and perhaps likely that these were exaggerated by the Spanish clergy.
The photograph used on this page was provided by the Field Museum for a part of their new exhibit Ancient Americas.