The abrupt rise of the Himalayas from the sea to the highest point on earth, along with the geologic and topographical complexity of the mountain system, has given it a wide range of ecological conditions, within a rise of just a few hundred kilometres. Add to this the fact that it is the confluence of two very different continental plates, each with its own flora-fauna and the meeting bringing forth an interesting cross-culturation as well, has created one of the most biodiverse regions in the world. There are about 10,000 species of plants, nearly a 1,000 species of birds, 300 species of mammals, and several reptiles and aquatic species as well; a significant number of these species are endemic to the region. The southern slopes of the Himalayas are very green, with alluvial plains and moist deciduous forests at the base, teeming with life, including several species of large mammals. Higher up there are temperate broadleaf forests and coniferous forests, and even higher beyond the tree line are alpine meadows with the rarest of plants, several possessing medicinal properties.
The soils at higher altitudes are made of rock fragments and are not very productive . Beyond 5,500 metres lies a zone of permanent ice and rocks. The northern slopes are believed to have been beautiful valleys before the birth of the Himalayas, and were gradually turned into deserts (Gobi, Taklamakan) as the Himalayas grew and grew. The relative strength of the monsoons finds a reflection in the ecological profile east to west along the mountain range, as well. The eastern foothills and low hills upto 2,000m display a rainforest ecology, the central region is a transitional semi-wet region, while the western division is an arid desert.