You're right, never thought about De Laurentiis producing the film, it's Italian after all :) . Both Mandingo and Drum were based on novels by American author Kyle Onstott though and apparently the novels (and the rest Onstott's Falconhurst saga) were as politically incorrect as the movies.
It would be nice if Paramount had revisited Mandingo. It's hard to believe that a major studio like Paramount and an A list director like Fleischer ever produced something like Mandingo, and with such a cast. You would expect Italians to come up with this, and they did of course, but not...