Question: Why is there conflict between Tutsis and Hutus?

Answer: The bloody history of Hutu and Tutsi conflict stained the 20th century, from the slaughter of 80,000 to 200,000 Hutus by the Tutsi army in Burundi in 1972 to the 1994 Rwanda genocide in which Hutu militias targeted Tutsis, resulting in a 100-day death toll between 800,000 and 1 million.

But many observers would be surprised to learn that the longstanding conflict between the Hutu and Tutsi has nothing to do with language or religion -- they speak the same Bantu tongues as well as French, and generally practice Christianity -- and many geneticists have been hard-pressed to find marked ethnic differences between the two, though the Tutsi have generally been noted to be taller.

Many believe that German and Belgian colonizers tried to find differences between the Hutu and Tutsi in order to better categorize native peoples in their censuses.

Generally, the Hutu-Tutsi strife stems from class warfare, with the Tutsis perceived to have greater wealth and social status (as well as favoring cattle ranching over what is seen as the lower-class farming of the Hutus). The Tutsis are thought to have originally come from Ethiopia, and arrived after the Hutu came from Chad. The Tutsis had a monarchy dating back to the 15th century; this was overthrown at the urging of Belgian colonizers in the early 1960s and the Hutu took power by force in Rwanda. In Burundi, however, a Hutu uprising failed and the Tutsis controlled the country.

(Read more on the history of Hutu and Tutsi conflict)

On April 6, 1994, the Hutu president of Rwanda, Juvénal Habyarimana, was assassinated when his plane was shot down near Kigali International Airport. The current Hutu president of Burundi, Cyprien Ntaryamira, was also killed in the attack.

This sparked the chillingly well-organized extermination of Tutsis by Hutu militias, even though blame for the plane attack has never been established. Sexual violence against Tutsi women was also widespread, and the United Nations only conceded that "acts of genocide" had likely happened after an estimated half-million Rwandans had already been killed.

After the genocide and the Tutsis regaining control, about two million Hutus fled to Burundi, Tanzania (from where 500,000 were later expelled by the government), Uganda, and the eastern part of the Democratic Republic of the Congo, where the great focus of Tutsi-Hutu conflict is today. Tutsi rebels in the DRC accuse the government of providing cover for the Hutu militias.