The Three Kingdoms of Nepal

Capitol of Patan

In 1482 the kingdom of Nepal split among the sons of King Yakshamalla. His six son at first tried to rule the kingdom together, but this not last long before the kingdom was split into three separate kingdoms, Kathmandu, Patan, and Bhaktapur. Ratnamalla was the first of the sons to split from the group seizing Kathmandu. The remaining portion of the kingdom was ruled jointly until the eldest brother died. These kingdoms were not unified until 1768.
http://countrystudies.us/nepal/8.htm