Probably the same reasons that we 'white' people do, or have you forgotten Northern Ireland, Kossovo, the French Revolution, World War I and II, the Russian revolution and the peasants revolt, Icould continue ad nauseum on the atrocities that all races and ethnicities visit upon each other?
Race or colour is not a marker or indicator for murder, it's just that currently certain areas of the world are in turmoil, simple as that, it'll change over the the big scheme of things just like everything else.