These auxiliaries acted as guides, translators, soldiers, explorers and porters, often outnumbering peninsular Spaniards by enormous degrees in their military formations.
Indian auxiliaries continued to be used by the Spanish to maintain control over their colonies in the Americas; frequently stationed on the frontier, they were often used to suppress anti-colonial revolts such as Arauco War.
[1] 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.
They often constituted the most numerous group of the conquerors' followers: During Hernán Cortés' campaign against the Aztecs from 1519 to 1521, he supplemented his meagre force of Spanish soldiers (numbering some 1,300) with hundreds of thousands of native auxiliaries, from various states such as Tlaxcala, Texcoco and Cholula.
The expedition of Pedro de Alvarado to Guatemala was composed of 480 Spaniards and thousands of auxiliary Indians from Tlaxcala, Cholula and other cities in central Mexico.