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
South American Rugby Championship for those years. In 2018, the format of the tournament was changed once again: six teams (Argentina, Brazil, Chile, Colombia, Paraguay and Uruguay) would play in the top division, which was renamed to "South American Six Nations". Argentina is the most dominant nation at the South American Championships, winning 34 of 40 editions, as well as the two editions of the CONSUR Cup, and the two editions of the Sudamérica Rugby Cup. Uruguay won the tournament four times (1981, 2014, 2016 and 2017), while Chile (2015) and Brazil (2018) won the South American title once. The first edition of the