Kigali remainder of the colonial era, as much of the administration took place in Ruanda-Urundi's capital Usumbura, now known as Bujumbura in Burundi. Usumbura's population exceeded 50,000 during the 1950s, and was the colony's only European-style city, while Kigali's population remained at around 6,000 until independence in 1962. Kigali become the capital upon Rwandan independence in 1962. The traditional capital was the seat of the "mwami" (Kings Yuhi V, Mutara III and Kigeli IV) in Nyanza, while the colonial seat of power was in Butare, then known as Astrida. Butare was initially the leading contender to be the capital of the
Kigali three administrative districts—Nyarugenge, which lies in the south west, Kicukiro in the south east, and Gasabo, which occupies the northern half of the city's territory. Kigali lies in a region of rolling hills, with a series of valleys and ridges joined by steep slopes. Kigali lies between the two mountains of Mount Kigali and Mount Jali, both of which have altitudes over , while the lowest areas of the city have an altitude of . Geologically, the city lies in a granitic and metasedimentary region, with lateritic soils on the hills and alluvial soils in the valleys. The Nyabarongo River,