King Leopold's Ghost by Adam Hochschild is the story of the Belgian Congo. In the second half of the 1800s, King Leopold of Belgium decided that Belgium needed colonies like other European countries had.
I have an impression of Belgium being a pretty forward thinking place, so the horrors that took place in the Congo under Belgians seem even worse than they already are. Experts estimate that 8-10 million natives died during the Belgian occupation. The Belgians were brutal. Leopold basically used slave labor to enrich himself while fooling the world into thinking his role in the Congo was a humanitarian one.
King Leopold's Ghost was pretty eye-opening. The Belgian Congo wasn't something I knew much about, though I know a little bit more about the region at a later date. It is the setting of The Poisonwood Bible, one of my favorite books.
Another favorite of mine is The Heart of Darkness, which was written by Joseph Conrad who visited the area. If you've read it you might think that Conrad exaggerated how bad things were. Not really. There were Belgian soldiers with heads on spikes.
King Leopold's Ghost isn't one of those non-fiction books that I'd suggest to anyone. It's not that easy of a read , but it covers some really incredible stuff that you might not know.