The altepetl was the local, ethnically-based political entity, usually translated into English as "city-state," of pre-Columbian Nahuatl-speaking societies in the Americas. The altepetl was constituted of smaller units known as calpolli and was typically led by a single dynastic ruler known as a tlatoani, although examples of shared rule between up to five rulers are known. Each altepetl had its own jurisdiction, origin story, and served as the center of Indigenous identity. Residents referred to themselves by the name of their altepetl rather than, for instance, as "Mexicas." "Altepetl" was a polyvalent term rooting the social and political order in the creative powers of a sacred mountain that contained the ancestors, seeds and life-giving forces of the community. The word is a combination of the Nahuatl words ātl and tepētl. A characteristic Nahua mode was to imagine the totality of the people of a region or of the world as a collection of altepetl units and to speak of them on those terms. The concept is comparable to Maya cah and Mixtec ñuu. Altepeme formed a vast complex network which predated and outlasted larger empires, such as the Aztec and Tarascan state.

Nahuatl, Aztec, or Mexicano is a language or, by some definitions, a group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about 1.7 million Nahua peoples, most of whom live mainly in Central Mexico and have smaller populations in the United States.