Little Big Man was an actual historical figure. He was a Native American, an Oglala Lakota, who was a fearless and respected warrior who fought under, and was rivals with, Crazy Horse. He also fought at the Battle of Little Big Horn, a battle which is depicted in this film.
The main tune played when the the 7th Cavalry were attacking on the Washita River and during the Battle of Little Big Horn is an Irish jig titled "Garry Owen". This song was the official song of the Seventh Cavalry of the U.S. Army - General Custer's cavalry. However, the music is actually a medley which consists of The Garry Owen and St. Patrick's Day