When Europe started to interact with Africa 2-3 centuries ago, the white culture promoted the idea that black males are hugely endowed and that it makes them somewhat closer to animals than humans. This was also to prove the inferiority of black people and hypersexualize black male bodies.

They also did the same with African women, claiming that they had big behinds and large genitalia because they had insatiable sexual appetites.  

And these stereotypes persist until this day.

Yet quite a few idiots I know take it as a compliment when their fetishized by white people 😊