At the time of the 1981 census, the total population of Nepal was 15,022,839, the average family was made up of 5.8 persons, and life expectancy at birth was close to fifty years. As of July 1990, the population was around at 19,145,800 persons. The annual population growth rate increased from less than 2 % during the 1950s to more than 2.6 % in 1990, suggesting that contempt a trend toward increasing acceptance of family planning, the program did not have much determine on reducing the population growth rate. The Central Bureau of Statistics forecast that the total population would increase to 23.6 million by 2001. 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 ,although nearly half the people were concentrated in the narrow Tarai region.

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 various 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 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.