This article intends to discuss the importance of use of maps during the political negotiation that result in the signature of the Treaty of Madrid, between Portugal and Spain, in 1750. Studies the process of "production" of the 1749's Mapa das Cortes, analyzing the sources utilized, and the distortions presented in it. Furthermore, discuss the importance of the map to Spain's recognition of the Portuguese's territorial claims in South America, in the middle of eighteenth century.
History of Cartography; Diplomacy; Mapa das Cortes
