The Belgian colonial rule, which rewarded Tutsis with a Western education, and denyied political and economic power to the Hutus
Rwandan Independence, in 1963, when the Tutsis were disciminated against, and went into exile in Uganda
The Civil War, when the Tutsis returned to Rwanda in 1990, a civil war broke out, ending in a cease-fire, signed by the Hutu president, and presided over by the United Nations peacekeeping force
President Habyariman, a Hutu, was shot down on April 6th, 1994. The Hutus blamed the Tutsi for this, and they started a massacre.