The Berlin band, which described itself as the first rock big band and at times comprised up to 12 musicians, emerged from two school bands and was founded in the late 1960s by guitarist Udo Arndt and three other musicians: Christoph Busse (dr, voc), Dietrich Markgraf (fl, sax) and Andreas Villain (b). As they found the English language too banal and German lyrics were associated with the schlager-pop image, they called themselves Os Mundi, Latin for ‘The World’. After their first album, they changed their musical style, influenced by numerous sessions with Agitation Free and by the expansion of the band to a sextet with the addition of two further members, Buddy Mandler (dr, perc, voc) and Mikro Rilling (cel, perc, voc). With great instrumental diversity and tempo variations, they played a mix of bluesy-jazzy, progressive hard rock defined by Udo Arndt’s solid guitar playing, and at times slightly funky jazz rock, featuring virtuoso solos on flute and saxophone.

In 1972, their second album, 43 Minuten, was released on the new Brain label, named after the approximate LP running time and produced by the legendary Conny Plank, who also played guitar on the final track. This LP was not a success either, despite being more of a progressive mainstream record than their debut. The band released no further albums after that, but continued to exist until 1975 with a steadily growing line-up. Despite the rather harsh reviews at the time, this LP was regarded by many as essential, and thus became a cult album and a must-have for every prog fan.