King had already been an R&B star for a dozen years by the time of his first live album, recorded in 1964 in Chicago — and that meant that he could appeal to his audience's nostalgia. Between songs, he keeps telling the crowd that now he's going to "go back." His singing is as mighty and fluid as it ever was here, flickering between sweet and rough and radiant tones without a hint of effort. The rock fans who were just starting to get into blues ate it up. Live at the Regal became King's first charting LP and inspired the blues-rock scene that was forming in the United Kingdom.

If you want to hear everything a B.B. King guitar performance can be, you may as well start here. After whipping through his customary show-opener, "Every Day I Have the Blues," with breakneck impatience, King lays into "How Blue Can You Get?" As befits the show's jailhouse setting, King's guitar is occasionally at its most abrasive. To begin "3 O'Clock Blues," he cuts off his conversational patter with a sharp, percussive, violent chord. And he turns in a definitive live version of "The Thrill Is Gone" that's both searing and soaring.

In 1971, King recorded one of his finest live albums, Live in Cook County Jail; and one of his most disappointing, Live in London, a collaboration with British bluesmen and rockers that never gets cooking. A third 1971 recording, Live in Japan, went unreleased in the U.S. until 1999, and here you can hear King spread out a little more than on those contemporary live recordings. Extended, largely instrumental workouts like "Niji Baby," "Hikari #88" and the nine-minute "Japanese Boogie," showcase a looser and jammier side of King that's less frequently documented.

Onetime rivals for R&B supremacy, the two blues greats hit the road together in the Seventies, where they soon discovered how well their styles complemented one another while bantering with expert comic timing. "Nothing is planned tonight," King announces early in this hour-long set, and whether or not that was true there's a spontaneous but never sloppy spark. It's instructive and exciting to hear King's guitar supporting another vocalist, particularly a master such as Bland. They continued to tour together regularly and released the second, far less exciting Together Again. . .Live in 1976.

The "Rumble in the Jungle" — the legendary 1974 Muhammad Ali/George Foreman boxing match in Zaire, documented in the film When We Were Kings — was accompanied by a three-day music festival, at which King was one of the headliners. Playing with members of his touring ensemble and a couple of the Crusaders, the band had been partying in Kinshasa for days by the night of their gig ("clothing was deemed optional, hedonism ruled, Caligula was an amateur," pianist Ron Levy later recalled). By the time they hit the stage, though, they were in top form, updating King's greatest hits with a touch of the era's smooth funk.