At the end of the tour to promote King Crimson's previous album, Islands, Fripp had parted company with the three other members of the band (Mel Collins, Boz Burrell and Ian Wallace).

The second recruit was Jamie Muir, a free-improvising percussionist who had previously been performing in the Music Improvisation Company with Derek Bailey and Evan Parker, as well as in Sunship (with Alan Gowen and Allan Holdsworth) and Boris (with Don Weller and Jimmy Roche, both later of jazz-rock band Major Surgery).

He was keen to leave the band before they embarked on their Close to the Edge tour, believing that the experimentation-oriented King Crimson would be a more expansive outlet for his musical ideas.

Muir's percussion rig featured eccentric instrumentation including chimes, bells, thumb pianos, a musical saw, shakers, rattles, found objects (such as sheet metal, toys and baking trays), and miscellaneous drums and chains.

The instrumental pieces carried strong jazz fusion and European free-improvisation influences, and some aggressive portions verging on heavy metal.

"[6] The album spawned the concert staple "Exiles", whose Mellotron introduction had been adapted from an instrumental piece called "Mantra" which the band's original lineup had performed throughout 1969.

In addition, a section of "Larks' Tongues in Aspic, Part One" was reworked from a piece entitled "A Peacemaking Stint Unrolls", which was recorded by the Islands-era band and finally released in 2010 as a bonus track on that album's 40th anniversary edition.

[22] AllMusic's retrospective review was resoundingly positive, marking every aspect of the band's transition from a jazz-influenced vein to a more experimental one as a complete success.

It deemed John Wetton "the group's strongest singer/bassist since Greg Lake's departure," and gave special praise to the remastered edition.