The Yungas (Aymara yunka warm or temperate Andes or earth, Quechua yunka warm area on the slopes of the Andes) is a bioregion of a narrow band of forest along the eastern slope of the Andes Mountains from Peru and Bolivia, and extends into Northwest Argentina at the slope of the Andes pre-cordillera. It is a transitional zone between the Andean highlands and the eastern forests. Like the surrounding areas, the Yungas belong to the Neotropical realm; the climate is rainy, humid, and warm. Setting The Yungas forests are extremely diverse, ranging from moist lowland forest to evergreen montane forest and cloud forests. The terrain, formed by valleys, fluvial mountain trails and streams, is extremely rugged and varied, contributing to the ecological diversity and richness. A complex mosaic of habitats occur with changing latitude as well as elevation. There are high levels of biodiversity and species endemism throughout the Yungas regions. Many of the forests are evergreen, and the South Andean Yungas contains what may be the last evergreen forests resulting from Quaternary glaciations. World Wildlife ecoregions The World Wide Fund for Nature has delineated three yungas ecoregions along the eastern side of the Andes: The northernmost is the Peruvian Yungas, located entirely within Peru and stretching nearly the whole length of the country. The Bolivian Yungas lies to the south, entirely within Bolivia. The Cordillera Apolobamba marks the boundary between the Peruvian Yungas and Bolivian Yungas. The Southern Andean Yungas begins in southern Bolivia and continues to the north of Argentina. It is a humid forest region between the drier Gran Chaco region to the east and the dry, high altitude Puna region to the west. Yungas are transitional zones between the Andean highlands and the eastern forests. The yungas forests are extremely diverse, ranging from moist lowland forest to evergreen montane forest and cloud forests. The terrain is extremely rugged and varied, contributing to the ecological diversity and richness. A complex mosaic of habitats occur with changing latitude as well as elevation. There are high levels of biodiversity and species endemism throughout the yungas regions. Many of the forests are evergreen, and the South Andean Yungas contains what may be the last evergreen forests resulting from Quaternary glaciations. Climate The average temperature is 72 °F (22 °C). The climate is varied and ranges from a humid tropical to the cold of the Andes over 10,000 ft (3,000 m).