Films about slavery are few and far between. In my lifetime, I've seen one - Amazing Grace from 2006. Wikipedia lists twelve (three of those are set for release in 2012 or 2013). A scant few compared with many hundreds - if not thousands - of films that have been made about the greatest crime against humanity in the twentieth century; holocaust films.
After the holocaust came a swell of films about the holocaust; providing an outlet for the widespread feelings of anger, horror, repentance and regret. They came from all sorts of countries, but German cinema especially was shaped by a generation of Germans looking back on their past. Likewise, in the wake of the Vietnam war, there were a flood of films that depicted the horrors that unfolded there, and called into question America's longstanding pride in superiority in warfare. The scars of the Vietnam war are still there, but it has been 'dealt with' on a cultural level. These films helped entire nations move on from the mistakes they've made; they are a result of and a part of the healing process. It's a trend that has gone on for centuries, and we see it now in today's trend of movies about wars in the Middle East.
But America hasn't finished dealing with its past yet. Django Unchained is an important movie because it is an American film about American slavery before the civil war. The practice is arguably more inhuman than the holocaust; treating entire people groups as animals to be commanded, traded, and bred. It was widespread around the world, and lasted far longer than the holocaust or any other genocide (for a solid rundown on the context of slavery, click here). And as I said before, there is relatively little in American popular culture that reflects on precisely what transpired across those decades.
