Progressive rock began in 1969 with King Crimson's album "In the Court of the Crimson King" and attempted to extend the boundaries of rock music through complex arrangements, virtuosic musicianship, and influences from genres like classical music and jazz. Key bands from 1969-1978 included King Crimson, Genesis, Emerson, Lake & Palmer, and Rush. Progressive rock faced a backlash in the late 1970s but has since seen a revival with bands new and old continuing to push musical and technical boundaries.