Political map of South American nations 26 November 1908 (Rio Branco's Treaties): The scramble for resources, especially rubber (Amazon rubber boom), in the South American interior in the late 19th and early 20th centuries saw a flurry of border settlements as the nations of the continent attempted to make the most of their old and conflicting claims without risking costly wars. Most successful was Brazil, which, thanks in large part to the diplomacy of the Baron of Rio Branco, consolidated its frontiers by negotiating numerous favorable treaties between 1895 and 1909.