This article presents the results of an investigation of the exchange of products between the border caravans from the Andean highlands and the sub-cordillera valleys which took place in the Codpa valley in northern Chile in the middle of the 20th century. Making use of a multi-situated and extended ethnographic case study, it offers a relational and contextual interpretation of the historical phenomenon of the marchantes and their practice of “leaving children” from indigenous communities on the Bolivian border with Chile. We analyze oral sources, complemented by documentary ones, to detail the experiences of local actors and their universe of meanings. As a result, we argue that the marchantes were “cultural mediators” in the (re) production of the alterity of the frontier, using sociocultural practices that were inscribed in local kinship customs.