History of the Democratic Republic of the Congo war and genocide in neighboring Rwanda had spilled over into Zaire. Rwandan Hutu militia forces (Interahamwe) who had fled Rwanda following the ascension of a Tutsi-led government had been using Hutu refugee camps in eastern Zaire as bases for incursions into Rwanda. In October 1996 Rwandan forces attacked refugee camps in the Rusizi River plain near the intersection of the Congolese, Rwandan and Burundi borders meet, scattering refugees. They took Uvira, then Bukavu, Goma and Mugunga. Hutu militia forces soon allied with the Zairian armed forces (FAZ) to launch a campaign against Congolese ethnic Tutsis in eastern Zaire. In turn,
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;