Beat music, British beat, or Merseybeat (for bands from Liverpool beside the River Mersey) is a pop and rock music genre that developed in the United Kingdom in the early 1960s. Beat music is a fusion of rock and roll, doo-wop, skiffle and R&B. The beat movement provided most of the bands responsible for the British invasion of the American pop charts in the period after 1964, and provided the model for many important developments in pop and rock music, including the format of the rock group around lead, rhythm and bass guitars with drums.