Answer:
The unification of Nepal officially began in 1743 AD (1799 BS) after King Prithvi Narayan Shah of Gorkha launched an aggressive annexation campaign seeking to broaden his own kingdom's borders. After conquering the Nepal Mandala, which consisted of the three separate city-states of the Kathmandu Valley, Kathmandu, Lalitpur and Bhaktapur, Shah moved his hilly capital in Gorkha to the fertile and wealthy city of Kathmandu and adopted the name Nepal for the entire Gorkha Empire.