Gaobie Jiabiangou
告别夹边沟 (lit. "Farewell to Jiabiangou")
Book about a group of several thousand exiled rightists who were sent into countryside exile, starved and died and did horrible things to stay alive. Written as a novel, but actually arose from the author's historical research. It wasn't banned, exactly, but you'd have an awfully hard time getting your hands on it these days.