Documentarian Leon Gast spent two months in Zaire and 22 years in editing rooms in order to create and complete "When We Were Kings", his 1996 documentary on the Muhammad Ali-George Foreman 'Rumble in the Jungle' heavyweight title bout and its profound affect on the African-American community. Originally intended to be a concert film, it evolved into a portrait of the youthful and popular Ali contrasted with the more subdued Foreman. Because of a postponement due to an injury to Foreman, the scheduled concert, headlined by James Brown and B B King, went on to nearly empty houses. Yet Gast kept his cameras rolling and ended up with some 300,000 feet of film. Over the years, he attempted to find financing to complete the film. Finally, with assistance from Taylor Hackford who suggested filming contemporary interviews with such notables as Norman Mailer and Spike Lee to frame the picture, Gast completed the documentary. After its premiere at the 1996 Sundance Film Festival, "When We Were Kings" went on to win numerous critical prizes and the Best Documentary Feature Oscar.

Gast studied dramatic arts at Columbia University, but dropped out without earning a degree in order to join a crew involved with the 1957-60 TV series "High Adventure With Lowell Thomas" which went on locales throughout the world. In the early 60s, he developed a reputation as a prominent photographer, often of fashion layouts, working for such magazines as ESQUIRE, VOGUE and HARPER'S BAZAAR. Although continuing in this line into the 70s, Gast also turned his attentions to documentary filmmaking. He exhibited a flair for musical subjects as evidenced by his "Our Latin Thing" (1972) and "Salsa" (1977) both anticipated the influence Latin American music would have on greater American pop culture during that decade (e.g., the Hustle dance craze). In 1977, Gast and Jerry Garcia co-directed "The Grateful Dead" concert and tour film, and Gast, Richard Chase, and Kevin Keating directed "Hells Angels Forever" (1983), the definitive work on the motorcycle clique. One of Gast's most mainstream forays was his editing and co-producing of the 1993 NBC docudrama "Fallen Champ: The Untold Story of Mike Tyson," a telefeature which chronicled Tyson's rise to heavyweight champion and his conviction on rape charges. Working in the milieu of prize fighting and concert films was a prelude to "When We Were Kings" and aided in his being hired for the job.

During the period, Gast also worked with Barbara Kopple editing several of her award-winning projects. The pair worked for over two years on "Woodstock 94", an uncompleted documentary on the reunion of the late 60s event. Propaganda Films withdrew its financial support at the last minute, leaving the film in limbo.