Geography of South America world by drainage area—the Amazon River and the more southerly Paraná River. The other major river of this central lowland is the Orinoco River, which has a natural channel linking it with the Amazon. Most of this central lowland is sparsely populated because the soils are heavily leached, but in the south is the very fertile pampas of Argentina—one of the world's major food-producing regions where wheat and beef cattle are pre-eminent. The natural vegetation of the northern lowlands are either savanna in the northern "llanos" and southern "campos", or tropical rainforest throughout most of the Amazon basin. Efforts to
Argentina–Uruguay relations and Uruguay were first established in the 1827 Peace Convention. In the period between the Peace Convention and the 1973 Boundary Treaty between Uruguay and Argentina in which are set most of the contemporary limits between both countries, the Uruguayan-Argentinian boundary was stablished just somewhere in the River Uruguay. According to what was called Zeballos's Doctrine due to Argentinian Chancellor between 1854 and 1923, Estanislao Severo Zeballos, Uruguay should had no jurisdiction at all over the River Plate that should only pertain to Argentina. During José Figueroa Alcorta's Argentinian presidency three mayor incidents encountered: In a treaty of June 18