Progressive rock ("prog") was a musical movement that reached its peak in the early 1970s and attempted to blend the visceral style of rock music with outside influences: classical, jazz, folk, and world musics, for example. There is no single all-encompassing definition of progressive rock. Much of it is more musically complex than other forms of rock, and most prog fans see this compositional complexity as a defining trait. In part because of this complexity and intellectualism, the movement of the 1970s was critically vilified because it was seen as a move away from the grassroots, working-class foundation of rock music. Contemptuously billed as pretentious and indulgent, the prog movement was a ripe target for the punk revolution of the late 1970s, which effectively wiped progressive rock off the face of the musical map. Popular bands associated with progressive rock include Yes, Jethro Tull, Emerson, Lake & Palmer, Marillion, King Crimson, Genesis, and Pink Floyd.