Why are so many people so quick to discredit black achievements?

I find it grossly absurd to see just how narrowminded people are in this day and age. The only thing blacks have done according to whites or should I say the narrowminded kind, were that blacks were just slaves and tribesmen, civil rights leaders, football and basketball stars with the occasional tennis or golf phenom. Why are you people so quick and vehement to discredit blacks? What makes you think that Cleopatra was not black? What makes you think that blacks are not the decendents of kings and queens? That we were only meant to tend the white mans fields? Cleopatra was of greek origin etc? Give me a break. There is a very strong and valid reason why blacks in this country were not allowed to read and right when brought too this country and guess who wrote all the history in our so called history books? White, oppressive white men who grossly misrepresent the achievements of blacks. If we truly went by the history written blacks in this world have done nothing. Wake up white folk