Ethnic cleansing in Darfur

We wont really know for sure how many people have already died in the brutal attacks by the Janjaweed and the Sudanese army but current estimates point that if this goes unchecked at least 300,000 thousand people will die of attacks and starvation (not to mention One million people have already been displaced). Finally, the African Union is sending troops to stabilize the region but it might already be too late.
I don't understand why the world simply turns away from these brutalities until its too late... do we want another flimsy operation by the so called police nations that led to the brutality of the Hutus and Tutsis ? Why do we forget so easily ? If a country claims to be the world's policeman then it should not play with the technicality of the word "genocide" or "ethnic cleansing".