In this work we presented the transcript of a document written by the legal cura Pedro Juan Andreu, entitled ‘Annulliates the Historical Mission of San Estevan de los Indios Lules 1744’. The manuscript is part of the novel De Angelis Collection, acquired and preserved by the National Library of Rio de Janeiro. The narrative suggests reporting on the state of play of the reduction and on the results of two specific tasks relating to the control of indigenous input groups, assigned by the provincial father during his annual visit. To address these issues, data on other issues relevant to the study of the inter-ethnic situation of the colonial period are included from a perspective that recognises the history of ethnic groups in Western Chaco. The critical remark accompanying this transcription is organised along two main lines: the first one to place the document in its various contexts; the second aims to identify and delineate the narrative data that will allow us to make progress in analysing different issues in indigenous history in particular and border studies in general.