The ethnic composition of Nepal is very complex given that in historical times populations of different cultures and origins have settled there, arriving in successive waves from practically all the neighboring regions. Only the descendants of the most ancient Nepalese populations belonging to the Mongoloid lineage, especially the Newari, which have been widespread in the Kathmandu Valley since time immemorial, can be considered autochthonous. Above 3000 m along the Tibetan border and in the high Himalayan valleys, other Mongoloid groups predominate, referred to as bhotia (or bhote), which use Tibetan-Burmese languages, to which we owe the introduction of the Tibetan culture and Lamaist Buddhism; the famous can be linked to them sherpas, formidable walkers and porters whose skill has often been proven during ascents to the Himalayan massifs. Also Mongoloid and Buddhist are other tribal groups such as the gurung in the W, the magar and the thakali in the center, and the kirati, including the rai in the Sun Kosi basin and the limbu in contact with Sikkim, in the easternmost part of Nepal. In the middle area of the territory, in addition to the ancient indigenous tribes, there are populations of Indo-European origin coming from the Ganges plain, some before the Christian era such as the Khasi, others in more recent times due to the pursuit of the Muslim invasions of the sec. XII and XIII. These populations did not settle above 2500 m because they were unable to adapt to the harsh mountain life and because they lack the necessary techniques to practice the activities typical of mountaineers. We owe them the introduction of Hinduism, which contemplates the subdivision of the population into castes, and of Indo-European languages such as nepālī, the language spread nationally by an ethnic group belonging to the Khasi, the Gorkhali, famous warriors who were often employed as mercenary soldiers by the British and Indians and that in the second half of the century. XVIII conquered Nepal. The result of the meeting of Indo-European and Mongoloid populations is the presence in Nepal of two cultural areas, Buddhist in the N and Hindu in the S, which merge in the Middle Himalayas, especially in the Kathmandu Valley, the heart of the country.
According to localtimezone, Nepal is the most populated of the Himalayan states; over 90% of the population inhabits the regions of the hills and valleys and the terai. The demographic increase has been remarkable: the population has practically quadrupled in the space of seventy years. The population, whose density is 183 residents/km², lives mainly in small villages (in 2008 only 17% could be classified as urban) and is unevenly distributed according to environmental situations: more densely packed in flat areas and in the valley floor, scattered in the higher areas, few and isolated in the high mountains. Thus, the most densely populated areas are the central region, where the capital is located, and the Lumbinī area, in the western region. Among the many small towns, the three cities of the Kathmandu Valley are of greater importance in terms of size, evidence of the past and cultural weight: the capital, Kathmandu, a commercial center and communications hub, famous for monuments and shrines, which attract a fair amount of tourists; Lalitpur, where an incredible number of temples and pagodas of extreme beauty are also concentrated; in the end, Bhaktapur, the third city in the country, with a variety of sacred buildings no less than the first two. The cities of Birātnagar, the second most populous city, located to the SE near the Indian border, Pokharā, in the western region, base city for high altitude tourism, and Wīrgañj (or Bīrgañj), border city, also exceed 100,000 residents. and gateway for those who come from India.
On the basis of the division by altitudinal climatic horizons it is possible to distinguish various bands of vegetation: in the terai, in the slopes and in the valley bottoms up to 1000-1500 m, the deciduous forest of sal dominates; in the warm temperate climate, man has considerably reduced the evergreen forest, made up mainly of oaks, a plant similar to the chestnut, the Castanopsis indica, and pines; in the cold temperate climate zones the vegetation consists of coniferous forests which are gradually replaced at higher altitudes by birch trees; in the subnival climate belt, there is a sparse tree vegetation and shrub and herbaceous associations of the alpine type, and finally above 5000 m, it is the undisputed dominion of the ice. Nepal is home to a remarkable variety of animals, mainly in the terai, including tigers, leopards, deer, elephants, rhinos, wolves, bears, yaks; the Ganges dolphin also lives in the country. The protected areas, which make up 16.6% of the territory, include 7 natural parks and various reserves; UNESCO has proclaimed two natural parks as World Heritage Sites, that of Sagarmatha in 1979 and the royal one of Chitwan in 1984. Main environmental emergencies are deforestation and soil erosion, caused by excessive use of wood as fuel; the air and water pollution in urbanized areas is also noteworthy, also caused by the lack of sewers in large cities. A recent phenomenon, linked to the increasingly frequent mountaineering expeditions organized on the Himalayan peaks, is the environmental pollution caused by human passage and by the waste produced by the various fields scattered at high altitude.