Although slavery existed all over the world for thousands of years, among people of every race, it was considered a "peculiar institution" in the United States because it was in complete contradiction to the principles on which the country was founded. Slavery was controversial among Americans when it was still accepted as just another fact of life in other countries.
Nowhere else in the world was such a literature of justification of slavery produced as in the antebellum South, because nowhere else was slavery under such sustained attack. An especially virulent racism arose to try to justify slavery, and this racism lasted long after slavery itself was gone.
That history and its painful consequences are undeniable. But, in a world where whole nations have in effect raised their IQs by 20 points in one generation, it is time for black "leaders" and white "friends" to stop trying to discredit the tests and get on with the job of improving the skills that the tests measure.
A number of black schools, even in rundown ghettos, have already reached or exceeded national norms on tests, so there is no question that it can be done. The question is whether it will in fact be done, on a large enough scale to change the abysmal educational results in too many predominantly black schools.
So long as demagogues are concentrating on demonizing anyone who points out the problem, do not expect the kind of general improvement that is needed. This demonization has made "The Bell Curve" one of the most misrepresented books of our time. But such demagoguery has not helped one black child to get a better education.