Phnom Penh also known as Krong Chaktomuk Serimongkul had it’s beginnings as the royal capital for 73 years, from 1432 to 1505, the city was later abandoned as a succession of civil wars broke out.
Even by Asian standards it is a young city, rising from the flood plans little more than 150 years ago. Today it is one of the region’s fastest growing cities- with every generation seeing such rapid development (and destruction) that it would be almost unrecognizable to the last.
It was Norodom I (reigned 1860-1904) who, in 1865, moved the royal court (along with some 10,000 subjects) to the area where the rivers of the Tonle Sap, Bassac and Mekong converge and began work on the Royal Palace soon after.
In full here.