Before the 1950s, African-Americans did not appear in leading roles in American movies, with the odd exception like Jackie Robinson playing himself in the low-budget 'The Jackie Robinson Story' (1950). It took Sidney Poitier to become the cinema's Jackie Robinson, the color barrier-breaker. Poitier did his best to slog through a series of socially relevant movies, all designed to comment safely on relations between blacks and whites, including 'The Defiant Ones' (1958), 'In the Heat of the Night' (1967) and 'Guess Who's Coming to Dinner' (1967). And so Poitier's career has become more historically important than it is interesting.
All this really wasn't so long ago in the grand scheme of things, and when 25 year-old Denzel Washington broke into movies in 1981, things hadn't changed much. His striking demeanor quickly caused him to be cast in more of those noble, socially relevant-type movies, like 'A Soldier's Story' (1984), as anti-apartheid activist Steven Biko in 'Cry Freedom' (1987) and as a black Civil War soldier in 'Glory' (1989). I suppose it goes without saying that those, and other movies of the time, focused on white characters in the lead roles and were directed by whites.