Bhutan has a land area of 38,394 square kilometres bordered by China in the north and India in the south. The country is not only landlocked but has one of the most formidable mountainous terrains in the world, ranging from 100 metres to 7,500 metres in height. The climatic conditions vary due to the mountainous nature of the country. The country is subject to the monsoon rain in summer, with a relatively dry winter. About 72 percent of the land area is covered by forests of temperate and sub-tropical species that are a natural habitat of a diversity of flora and fauna. The country has one of the richest biodiversity in the world with about 3,281 plant species per 10,000 square kilometres and has been declared as part of one of the ten global biodiversity ‘hotspots’. The country is also endowed with a river system that has an estimated potential to generate 30,000 MW of hydroelectricity. The four major rivers, Amo Chhu, Wang Chhu, Punatsangchhu, and the Drangme Chhu and their tributaries have carved fertile valleys in central and western parts of the country, and provide irrigation to the southern and eastern plains before flowing into the Brahmaputra river basin. The steep and unstable terrain and the relatively young mountain system however render the country to be ecologically very fragile. Agricultural production is also severely constrained, as only around 16 percent of the land area is cultivable. The population of the country was estimated to be 658,000 in the year 2000. The population is largely rural with 79 percent of the population still living in villages despite a growth in urban drift in recent years. It is estimated that 39.1 percent of the population is under the age of 15. While there are several language groups and communities, the country is essentially composed of two broad ethnic groups, the Drukpas who are mongoloid and are of Buddhist faith making up 80 percent of the population, and people of ethnic Nepalese origin who are mainly indo-aryan and of Hindu faith. Administratively, the country is divided into 20 Dzongkhags composed of 205 Gewogs.