Rwandan Revolution posed by the refugees until the 1990s, when a civil war initiated by the Tutsi-refugee "Front Patriotique Rwandais" (FPR) forced the Hutu government into negotiations. This led to a rise in Hutu extremism and the 1994 genocide, in which hundreds of thousands of Tutsi were killed before the FPR took control. The earliest inhabitants of what is now Rwanda were the Twa, a group of aboriginal pygmy hunter-gatherers who settled the area between 8000 and 3000 BC and remain in the country today. Between 700 BC and 1500 AD, a number of Bantu groups migrated into Rwanda and began clearing
Hutu of Rwandan national unity, but has been criticized as an attempt at historical revisionism. Still others suggest that the two groups are related but not identical, and that differences between them were exacerbated by Europeans, or by a gradual, natural split, as those who owned cattle became known as Tutsi and those who did not became Hutu. Mahmood Mamdani states that the Belgian colonial power designated people as Tutsi or Hutu on the basis of cattle ownership, physical measurements and church records. There is an ongoing debate as to whether the Hutu and Tutsi are really separate groups or not;