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 border former Eastern Band of the rest of the Viceroyalty of Rio de La Plata. Depending on the presence of this river, the border between Uruguay and Argentina was not disputed. From 1815 to 1816 the government of the United Kingdom of Portugal, Brazil and the Algarves (Brazil before independence) tried to annex the region of the current Uruguay to Brazil. This occurred with the Brazilian victory against Uruguay during the Battle of Tacuarembó in 1820. The region was called Province of Cisplatina of already independent Empire of Brazil. It was echoed by Uruguayan supported by troops from Argentina on 25