Tropical grasslands, or savannas, are also the homes of primates in Africa and Asia; no savanna-living primates exist in South America. Tropical grasslands comprise a mixture of trees and grasses, the proportion of trees to grass varying directly with the rainfall. Campos in Brazil and Lianos in Venezuela are the examples of tropical grasslands. Lianos and Campos are grasslands found in South America. Lianos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the flooded grasslands and savannas biome.