The differences between groups in the former Yugoslavia have little to do with race (as most Americans would understand the term). It's tough to tell the difference between a Croat and a Serb just by looking at them. Conflicts were based more on culture, religion, language, and perhaps something akin to "tribal" identity (not literally tribes but I don't know how else to describe it). Some of these conflicts date back to the 14th century.
The only significant group in the region which some might identify as a distinct "race" are the Roma. That minority lives in all of the countries and they didn't cause countries to split up.
The only significant group in the region which some might identify as a distinct "race" are the Roma. That minority lives in all of the countries and they didn't cause countries to split up.