Chichimeca (Spanish [tʃitʃiˈmeka] ) was the name that the Nahua peoples of Mexico generically applied to many bands and tribes of nomadic and semi-nomadic peoples who inhabited northern modern-day Mexico. Chichimeca carried the same sense as the Roman term "barbarian" to describe people living outside settled, agricultural areas. The name and its pejorative sense was adopted by the Spanish. For the Spanish, in the words of scholar Charlotte M. Gradie, "the Chichimecas were a wild, nomadic people who lived north of the Valley of Mexico. They had no fixed dwelling places, lived by hunting, wore no clothes and fiercely resisted foreign intrusion into their territory, which happened to contain silver mines the Spanish wished to exploit."
In modern times only one ethnic group is customarily referred to as Chichimecs, namely the Chichimeca Jonaz of whom a few thousand live in the state of Guanajuato.
The Chichimeca peoples were many groups of varying ethnicities and speaking distinct languages from different families. As the Spaniards worked towards consolidating the rule of New Spain over the indigenous peoples during the sixteenth and seventeenth centuries, the Chichimecan tribes resisted. A number of ethnic groups of the region allied against the Spanish. The first and most long-lasting of these conflicts (1550–91) was the Chichimeca War.