The rivalries between Serb, Croat and Muslim communities in Yugoslavia date back centuries. Created in the aftermath of World War I, the country was first known as the Kingdom of Serbs, Croats and Slovenes. The name Yugoslavia was adopted in 1929. During World War II, Croats joined the Nazis in exterminating Serbs and others. The Serbs took up arms -- and hundreds of thousands of soldiers and civilians were killed on both sides.