An anthropological view on the “decivilising” work of the Salesian missionaries in the Upper Rio Negro Region (Brazilian Amazonia). In her quest for elements on indigenous cultures in the Upper Rio Negro region, on the history of these societies’ first encounters with Europeans and on the development of epidemics, the author consults documents drafted by the Salesian missionaries about the region from 1915 onwards. Reading these archives leads her to denounce the missionaries’ destructive practices, and to reveal the texts’ inexactitudes and the systematic criticisms made of local societies.