Bury My Heart At Wounded Knee is full of very famous historical events.
The film opens with the Battle of Little Bighorn, where Custer and his 7th cavalry were slaughtered by the Sioux under Crazy Horse and Sitting Bull. Sitting Bull’s defeat and his eventual escape into Saskatchewan are also factual. His eventual return and surrender of his rifle at the Standing Rock reservation are also factual.
The conditions at Standing Rock as well as the outbreaks of Whooping Cough and Measles so graphically portrayed are also true. Senator Dawes, played by Aiden Quinn, really did exist and tried to improve the lot of Native Americans by passing the Dawes Act, which sold thousands of acres of Sioux land, including the Black Hills, to white settlers for a pittance. This was also shown correctly in the film.
The young doctor played by Adam Beach is also based upon a real life individual who worked at the reservations and also worked with Dawes to improve the life of the Natives there.
The circumstances of Sitting Bull’s death as well as the facts regarding the massacre at Wounded Knee are also very factual. The evolution of the Ghost Dance ritual are also true.
So, in short, most of the films major plot points are indeed fact.