The Aché are a formerly uncontacted Indigenous group in Eastern Paraguay that had their population and traditional hunter-gatherer lifestyle largely decimated in the latter half of the 20th century. In the 1960s and 1970s, the community was relocated into colonies, where their numbers sharply declined due to various factors, including resettlement, kidnappings, infanticide, and exploitative labor practices. International attention surrounding their plight prompted various European and American anthropologists, activists, and human rights groups to interact with the community, leading to conflicting accounts on whether or not genocide had occurred. Throughout our research, we analyzed primary and secondary materials from library collections and archival records that reflect both perspectives. Some argue that the Paraguayan government had perpetuated genocide while others contend that the Aché’s decline was a tragic yet ‘inevitable’ result of broader contextual forces. Through our sources, we found that this debate highlighted scholarly conflict within the fields of anthropology and biology, and that it contributed to the re-emergence of terms such as "ethnocide."