Jostling Sovereignties: Wandering Peoples and Mapmakers in the Río de la Plata, 1700–1805

This paper analyzes the relationship between mapmaking and nomadic native peoples in a South American borderland. During the second half of the eighteenth century, the Portuguese and Spanish crowns financed joint mapping expeditions to determine a border between their South American kingdoms. Giving special attention to the Río de la Plata, a region corresponding with modern day Uruguay, northeastern Argentina, and Southern Brazil, Luso-Hispanic demarcation parties traversed open plains and raised stone markers to signal geographical limits. These two mapping campaigns represented the resolution of nearly a century of interimperial dispute over territorial possession and legal sovereignty in the region. Prior to the first expedition, which was commissioned under the Treaty of Madrid in 1750, representatives of the Portuguese crown had relied upon the idea of an “Ilha Brasil,” and later uti possidetis, to justify their claims. For their part, Spanish diplomats had argued that the Río de la Plata countryside was theirs under the authority of the centuries-old Treaty of Tordesillas.

While the mapping expeditions of the Treaty of Madrid, and later the Treaty of San Ildefonso, resolved the competing Iberian logics of possession, they also revealed the key contradictions of imperial sovereignty. Mapmakers were attempting to divide lands that were effectively possessed by a variety of nomadic native peoples, principally Charrúas and Minuanos, rather than the two crowns. This paper uses the vast corpus of documentation produced through the demarcation efforts in order to highlight local claims to sovereignty that they aimed to overwrite. It focuses particularly on the ways in which Charruas and Minuanos first disrupted the mapping expeditions and later took advantage of the practice of a border in order to develop informal economies of exchange.