Nepal had a population of 18,462,081 at the time of the 1991 census. The average population density at the time was 125 persons per sq km (329 per sq mi), although nearly half the people were concentrated in the narrow Tarai region. In contrast, the 2001 population estimate was 25,284,463. The population has grown rapidly since 1950 when there were only 9 million people. Although the government has sponsored family planning since the 1950s, these programs have been slow to affect Nepal’s population growth. In 2001 the population was increasing at an annual rate of 2.3 percent. Only 12 percent of the population lived in urban areas in 1999. Major cities include Kathmandu, Lalitpur (Patan), Bhaktapur, Biratnagar, and Birganj.

The large-scale migrations of Mongoloid groups from Tibet and Indo-Aryan people from northern India, which accompanied the early settlement of Nepal, have produced a diverse linguistic, ethnic, and religious pattern. Nepalese of Indo-Aryan ancestry comprise the people of the Tarai, the Pahari, the Newar, and the Tharus—the great majority of the total population. Indo-Aryan ancestry has been a source of prestige in Nepal for centuries, and the ruling families have been of Indo-Aryan and Hindu background. Most of the Tibeto-Nepalese groups—the Tamang, Rai, Limbu, Bhutia (including the Sherpa), and Sunwar—live in the north and east, while the Magar and Gurung inhabit west-central Nepal. The bulk of the famous Gurkha contingents in the British army have come from the Magar, Gurung, and Rai groups.