How did the war start?

The war has its roots in the aftermath of the conflict in neighbouring Rwanda in 1994. This was a civil war between two ethnic groups, the Hutu and the Tutsi, which left an estimated 1 million dead in 100 days (April-July 1994). Most of these were Tutsis, killed in a systematic genocide at the hands of Hutu militias. However, Tutsi forces (the Rwandan Patriotic Front) ended up victorious and overthrew the Hutu regime. Fearing retaliatory genocide, around a million Hutus (many of them genocidaires—those who had committed the genocide) fled the country into Congo, which was at the time called Zaire.