Much of the interior highlands consist of grassland. The largest expanse of grassland, the Rupununi Savannah, covers about 15,000 square kilometers in southern Guyana. This savannah also extends far into Venezuela and Brazil. The part in Guyana is split into northern and southern regions by the Kanuku Mountains. The sparse grasses of the savannah in general support only grazing, although Amerindian groups cultivate a few areas along the Rupununi River and in the foothills of the Kanuku Mountains. The country of Guyana consists of four main natural regions: The hilly sand and clay region, the interior Savannah, the forested highlands and the low coastal plains.