The northern region of Bhutan consists of an arc of glaciated mountain peaks with an extremely cold climate at the highest elevations. Most peaks in the north are over 7,000 m above sea level; the highest point is the Kula Kangri, at 7,553 m, and Gangkhar Puensum, at 7,541 m, has the distinction of being the highest unclimbed mountain in the world. Watered by snow-fed rivers, alpine valleys in this region provide pasture for livestock, tended by a sparse population of migratory shepherds. The Black Mountains in central Bhutan form a watershed between two major river systems: the Puna Tshang Chhu and the Drangme Chhu. Peaks in the Black Mountains range between 1,500 m and 2,700 m above sea level, and fast-flowing rivers have carved out deep gorges in the lower mountain areas. Woodlands of the central region provide most of Bhutan’s forest production. The Kuri Chu, Mangdi Chu, Drangme Chu, Puna Tsang Chu and Amo Chu are the main rivers of Bhutan, flowing through this region. Most of the population lives in the central highlands.
In the south, the Southern foot Hills are covered with dense, deciduous forests, alluvial lowland river valleys, and mountains up to around 1,500 m above sea level. The foothills descend into the subtropical Duars plain. Most of the Duars is located in India, although a 10â€“15 km wide strip extends into Bhutan. The Bhutan Duars is divided into two parts: the northern and the southern Duars. The northern Duars, which abuts the Himalayan foothills, has rugged, sloping terrain and dry, porous soil with dense vegetation and abundant wildlife. The southern Duars has moderately fertile soil, heavy savannah grass, dense, mixed jungle, and freshwater springs. Mountain rivers, fed by either the melting snow or the monsoon rains, empty into the Brahmaputra river in India. Over 70% of Bhutan is forested. The climate in Bhutan varies with altitude, from subtropical in the south to temperate in the highlands and polar-type climate, with year-round snow, in the north. Bhutan experiences five distinct seasons: summer, monsoon, autumn, winter and spring. Western Bhutan has the heavier monsoon rains; southern Bhutan has hot humid summers and cool winters; central and eastern Bhutan is temperate and drier than the west with warm summers and cool winters.