The mondo documentaries were a fad in the sixties carrying on till the seventies and even the early eighties. The genre was born in the hands of Gualtiero Jacopetti and Franco Prosperi in their dubious early film Africa Addio (1966) that was blamed for racism in its depiction of what happens to Africa after the white Europeans leave the continent.
I haven't seen Africa Addio, but I just recently saw another film by the same duo, called Addio Zio Tom AKA Goodbye, Uncle Tom (1971). It's another exploitation documentary, using lots of footage of sex, rape, killing, maiming and torture. It's also a political film, since it's about the rise of Black Power in America in the late sixties and about the slavery of the earlier centuries. All the scenes are acted out, as there are understandably no archive films about the time of slavery. This is by no means as clever as the Cuban The First Charge of Machete.
Goodbye, Uncle Tom is a very shocking film with all its violence and gratuitous sex, including even minors. It's clear that the directors want very much to condemn the exploitation of slave business and the bad treatment of the Africans, but still they use it to depict sex and violence to attract audience. Goodbye, Uncle Tom is a very confusing film: I really didn't know what to think about it. It's also a bit too long, but the main problem is that it never really gives the word to the Africans or the Black Power activists of the sixties (it even at times ridicules the African-Americans of the late sixties, either for the lack of political consciousness or at their funny seriousness), and with this gesture it becomes clear that Jacopetti and Prosperi want to shout at white Americans: "Watch out, the niggers are coming and it's all your fault!"
More Overlooked Films at Todd Mason's blog.
Edit: Earlier I had used Mondo Case as an example, but I was pointed out that I was actually talking about Africa Addio.