Following the Civil War, black Americans, through employment as musicians playing European music in military bands, developed a new style of music called ragtime which gradually evolved into jazz. In developing this latter musical form, African Americans contributed knowledge of the sophisticated polyrhythmic structure of the dance and folk music of peoples across western and sub-Saharan Africa. These musical forms had a wide-ranging influence on the development of music within the United States and around the world during the 20th century.