Atrás del Cosmos have been called Mexico’s first free jazz ensemble. Founded in 1975 by pianist Ana Ruiz, saxophonist Henry West, and percussionist Evry Mann, the trio soon became a central force in Mexico City’s creative arts community, mentoring a generation of improvisers, incorporating a revolving cast of artists into their immersive happenings, and sustaining a scene through their legendary weekly performances at El Galeón theater. The group’s celestial name stems from the reality of these daily activities: untold hours spent living and rehearsing in a residential building behind (‘atrás) the Cosmos cinema, honing their improvisatory alignment with the kind of everyday intensity that animated the Arkestra pad in Philadelphia or the Tapscott houses in Los Angeles. In 1977, Atrás invited Don Cherry to play and instruct on his organic approach to music and improvisation, leading to new levels of national recognition for the group. Despite their catalytic creative presence in Mexico City between 1977 and 1983, Atrás never broke through abroad—not least because they were rarely recorded and only released a single cassette before their disbandment.