The River Plate Basin (the confluence of the Parana and Uruguay rivers, both of which have their sources in Brazil) in the far south is more varied, higher and less heavily forested. North of the Amazon are the Guiana Highlands, partly forested, and partly stony desert. The Brazilian Highlands of the interior, between the Amazon and the rivers of the south, form a vast tableland. The Mato Grosso, from which rise mountains in the southwest, form a steep protective barrier from the coast called the Great Escarpment, breached by deeply cut river beds. The population is concentrated in the southeastern states of Minas Gerais, Rio de Janeiro and Sao Paulo. The city of Sao Paulo has a population of over 10.8 million, while over 6 million people live in the city of Rio de Janeiro.