Goodbye Uncle Tom (1971)

Goodbye Uncle Tom is a 1971 Italian film directed by Mondo film documentary directors Gualtiero Jacopetti and Franco Prosperi with music by Riz Ortolani. It is a pseudo-documentary in which the filmmakers go back in time and visit antebellum America, using period documents to examine, in graphic detail, the racist ideology and degrading conditions faced by Africans under slavery. Because of the use of published documents and materials from the public record, the film labels itself a documentary, though all footage is restaged using actors. Though the film is presented as a documentary, the fantasy framing device of the directors travelling back in time combined with the re-staging of historical events make it one of the earliest known mockumentary films.

More at Wikipedia.