The ecoregions of Bhutan generally vary according to altitude and precipitation. Bhutan occupies 38,394 square kilometres (14,824 sq mi) in the eastern Himalaya, at altitudes ranging from 97 metres (318 ft) to 7,570 metres (24,840 ft). The dry, plain-like valleys of western and central Bhutan tend to be relatively densely populated and intensely cultivated. The wetter eastern valleys, however, tend to be steeper, narrower ravines. At lower and middle elevations, Indomalayan biomes range from tropical and subtropical forests to temperate coniferous forests. In the northern mountainous regions, Bhutan is largely Palearctic, comprising temperate coniferous forests, montane grasslands and shrublands, and swaths without any ecozone in its highest glacial elevations.