Sweet Sweetback's Baadassss Song is a right-on seminal confrontational black-power oriented film with a thin story line about a black male prostitute on the run from "The Man" and a clutch of stylistic features that inspired a raft of 1970s blaxploitation films.
Melvin Van Peebles financed it, produced, wrote, directed and starred in it, as well as composing the music, making it a exemplary achievement in the contemporary legitimation of Black culture, not least of all because it was a huge financial success. Unfortunately Peebles never developed that success and it was not until Spike Lee's Do The Right Thing (1989) that Black cinema produced a work as controversial.
FYI: The director's son, Mario Van Peebles made a film about his father's film, Baadassss! in 2004.