The back story behind this concert CD is that, in September 1965, Charles Mingus performed at the Monterey Jazz Festival. He had done so triumphantly well the year before, however, Mingus' 1965 set was inexplicably cut short at a half-hour (Mingus himself claims 20 minutes) and so the material he had planned for the event, much of it newly composed, was instead unreeled at UCLA a week later.