Tutsi (largest) and the Twa (smallest). Small numbers of Hema, Kiga and Furiiru people also live near the Tutsi in Rwanda. The Northern Tutsi who reside in Rwanda are called Ruguru (Banyaruguru), while southern Tutsi that live in Burundi are known as Hima, the Tutsis who resides in Masisi which is in Kivu and they are known as Banyamasisi and the Tutsi that inhabit the Kivu plateau in the Congo go by Banyamulenge. The definitions of "Hutu" and "Tutsi" people may have changed through time and location. Social structures were not stable throughout Rwanda, even during colonial times under the Belgian
Origins of Hutu, Tutsi and Twa area may have assimilated some South Cushitic pastoralists. In general, the Tutsi appear to share a close genetic kinship with neighboring Bantu populations, particularly the Hutu. However, it is unclear whether this similarity is primarily due to extensive genetic exchanges between these communities through intermarriage or whether it ultimately stems from common origins: [...]generations of gene flow obliterated whatever clear-cut physical distinctions may have once existed between these two Bantu peoples – renowned to be height, body build, and facial features. With a spectrum of physical variation in the peoples, Belgian authorities legally mandated ethnic affiliation in the 1920s, based