As the Avant Garde movement tore down every wall of the old establishment, only one rule that had stood from the very inception of jazz remained: no accordions. —Genius Guide to Jazz, May 2001 Jazz is a musical genre that originated in the United States during the early 20th century. Jazz was popular during it's apex in the 50s and 60s and still is. It spawned many varieties such as bebop, modal, Latin, hard bop, and fusion.