There are a few different keywords for this. Harem is a good one to do a search on. Also there is Abducted, Sex Trade (may give you prostitutes as well however), and while it may not be quite what you want Black Master.
Alternately, just go in interracial, many of the stories in there are of black men and white women. Most of the stories I've come across of a black man doing a white gal she is pretty darn subservient to him. I'm not real sure why I mean the black guys I've met and will admit to have been just regular old folk.
In the stories however they are dominant and gangsta, like black men grew up in the wilds of south L.A. where it's carry a gun and mind your color choices or be shot dead and everybody hates the black guy so they hate right on back because they are better. Also shutting up about this because there's no actual explanation.
I've scored a few of your stories 5, too. Your writing is damned good, if you didn't totally suck as a human being youd be great. You remind me of Elmore Leonard. JamesBJohnson
I guess I'm not a secret anymore, ya'll love me.