Among the small hill states struggling for power during the later Malla period was Gorkha (see Glossary), founded in 1559 by Dravya Shah in an area chiefly inhabited by Magars. Legends trace his dynasty to warrior princes who immigrated from Rajputana in India during the fifteenth century. During its early fight for existence, the House of Gorkha stayed out of the two major confederations in western Nepal. No major expansion of the kingdom occurred until the reign of Ram Shah, from 1606 to 1633, who extended his territories slightly in all directions. During the seventeenth and early eighteenth centuries, Gorkha continued a slow expansion and appeared increasingly often as an ally of one or more of the three kingdoms in their quarrels with each other, giving the rulers of the hill state experience in the affairs of the Kathmandu Valley. Nar Bhupal Shah (reigned 1716-42) extended his lands toward the Kairang Pass in the north and Nuwakot in the east. He attempted to take Nuwakot and failed, but he did arrange the marriage of his son to the daughter of the raja of Makwanpur.

This son, Prithvi Narayan Shah (reigned 1743-75), made full use of his position to achieve supreme power and was one of the great figures in Nepalese history. Following in his father's footsteps, he apparently dedicated himself at an early age to the conquest of the valley and the creation of a single state. Before going on the offensive, he traveled to Banaras, or Varanasi, to seek financial assistance and purchase armaments, thus obtaining a personal view of conditions in the outside world, especially the position of the British East India Company. On his return to Gorkha, he established a number of arsenals and trained his troops to use the more modern weapons he had obtained in India. He arranged alliances with, or bought the neutrality of, neighboring states.

When King Ranajit of Bhadgaon (reigned 1722-69) quarreled with King Jayaprakasa of Kathmandu (reigned 1735-68), Prithvi Narayan Shah took Nuwakot and laid siege to Kirtipur, which was controlled by the king of Patan, Tej Narasimha (reigned 1765-68). During the fighting, Prithvi Narayan Shah was almost killed, and when his troops failed to take the town, he withdrew. At this point, he changed direction, as the Gorkhas were to do effectively time and again. The Gorkhas instituted a blockade of the entire valley, closed off all trade routes, and began executing blockade runners. Gorkha agents remained active in the towns, and the army attempted to starve the valley into submission.

When a second siege of Kirtipur also was unsuccessful, Prithvi Narayan Shah turned his attention toward Lamji, one of the Chaubisi principalities, and overran it after several bloody battles. The Gorkha army reappeared at Kirtipur. After a siege of six months, the town was treacherously delivered to the Gorkhas, and its inhabitants were deliberately mutilated. The Gorkhas moved on to Patan in 1767, but their attention was diverted by the appearance of a 2,400-man expeditionary force sent by the British East India Company to aid the traditional kings of the valley. The British column, ravaged by malaria contracted in the Tarai, had to withdraw quickly without accomplishing anything other than delaying the Gorkhas. This token opposition by the British, however, was not forgotten by Prithvi Narayan Shah and his successors. With the field again clear, on September 29, 1768, Gorkha troops infiltrated Kathmandu while the population was celebrating a religious festival and took the town without a fight. Jayaprakasa fled to Bhadgaon with Tej Narasimha and Prithvi Narayan Shah was crowned king of Kathmandu. He soon entered Patan unopposed and then moved against villages east of Bhadgaon, arriving before the town the next year. His troops were admitted into Bhadgaon by nobles who had been bought off. Ranajit retired to Banaras, Jayaprakasa retired to die at the shrine of Pashupatinath, and Tej Narasimha died in prison. For the first time, the hill ruler, the raja of Gorkha, had become sole ruler in the Kathmandu Valley. One of his first acts in 1769 was to expel permanently from his territories all foreigners, including traders, Roman Catholic missionaries, and even musicians or artists influenced by northern India's style.

The conquest of the three kingdoms was only the beginning of a remarkable explosion of Gorkha military power throughout the Himalayan region. Prithvi Narayan Shah quickly made a movement toward the Chaubisi states in the west, but after encountering resistance in Tanahu, the Gorkha armies drove east into the Kirata country, overrunning all of eastern Nepal by 1773. They were poised for the invasion of Sikkim, but because its rulers came from Tibet, Sikkim was viewed as a client of Tibet (and thus of the Chinese). A warning from Tibet and the death of Prithvi Narayan Shah in 1775 stalled hostilities, but a full-scale invasion began in 1779. Resistance was encountered until 1788, when Gorkha forces drove the ruler of Sikkim into exile in Tibet and occupied all of western Sikkim. Guerrilla warfare continued as the Gorkhas constructed a base near Vijaypur to administer the eastern conquests. In the west, a marriage alliance with the rajas of Palpa kept them quiet while General Ram Krishna Rana conquered Tanahu and Lamjung (Gorkha's traditional rival) and advanced to Kaski by 1785. By 1790 all rulers as far as the Kali River had submitted to the Gorkhas or had been replaced. Even farther to the west lay Kumaon, in the throes of civil strife between two coalitions of zamindar (large landowners responsible for tax collection in their jurisdictions), who struggled to control the monarchy. One group invited the intervention of the Gorkhas, who defeated local forces in two battles and occupied the capital, Almora, in 1790. The Gorkhas were poised for greater adventures, but by then they were irritating bigger players and began to encounter resistance to their ambitions.

Data as of September 1991