Abstract: The growth of the field of ethnohistory on Argentina’s southern frontier has revolutionized Argentine historiography, challenging historians to rethink time-worn subjects as they considered Indigenous peoples’ experiences. This article contends that historians should prioritize decolonizing the field through putting Indigenous peoples’ experiences and ways of thinking at the center of their analyses rather than the government and settler frameworks that are most available in source material. Expanding the range of geographic and temporal frameworks that are deployed in historical studies will also help refocus attention on the events that were most important for these people. “Indigenizing” the study of Argentina’s Indigenous people is a worthy goal and a necessary step toward understanding the Indigenous world of tierra adentro on its own terms.