Jazz originated in the southern United States in the late 19th century and has since evolved into many styles. It began as ragtime, developed into New Orleans jazz which emphasized improvisation, and the big band swing era followed. Bebop emerged in the 1940s as a more complex style focused on instrumental virtuosity. Major innovators included Louis Armstrong, Duke Ellington, Dizzy Gillespie, and Miles Davis, whose modal and fusion styles influenced the development of jazz.