Auxiliary Indians or indios auxiliares is the term used in old Spanish chronicles and historical texts for the indigenous peoples who were integrated into the armies of the Spanish conquerors with the purpose of supporting their advance and combat operations during the Conquest of America. They acted as guides, translators, or porters and in this role were also called Yanaconas, particularly within the old Inca Empire and Chile. The term was also used for formations composed of indigenous warriors or Indios amigos (friendly Indians), which they used for reconnaissance, combat, and as reserve in battle. The auxiliary Indians remained in use after the conquest, during some revolts, in border zones and permanent military areas, as in Chile in the Arauco War.
The formations of auxiliary Indians arose commonly from alliances established by the Spaniards, exploiting ethnic and tribal antagonisms that they found during their occupation of the territory they were attempting to conquer. Hernán Cortés was one of the first captains who was known to strengthen his columns with these natives. Commonly after the conquest these auxiliary Indians were divided among the settlers of the territories already conquered. They often constituted the most numerous group of the conquerors' followers: