Rainbow are a British/American rock band formed in London and Los Angeles in 1975 by guitarist Ritchie Blackmore. Established in the aftermath of Blackmore's first departure from Deep Purple, they originally featured four members of the band Elf, including their singer Ronnie James Dio, but after their self-titled debut album, Blackmore fired these members, except Dio, recruiting drummer Cozy Powell, bassist Jimmy Bain and keyboardist Tony Carey. This line-up recorded the band's second album Rising (1976), while Long Live Rock 'n' Roll (1978) saw Bob Daisley and David Stone replace Bain and Carey, respectively. Long Live Rock 'n' Roll was also the last album with Dio before he left the band to join Black Sabbath in 1979.

Deep Purple are an English rock band formed in London in 1968. They are considered to be among the pioneers of heavy metal and modern hard rock, although their musical style has varied throughout their career. Originally formed as a psychedelic rock and progressive rock band, they shifted to a heavier sound with their 1970 album Deep Purple in Rock. Deep Purple, together with Led Zeppelin and Black Sabbath, have been referred to as the "unholy trinity of British hard rock and heavy metal in the early to mid-seventies". They were listed in the 1975 Guinness Book of World Records as "the globe's loudest band" for a 1972 concert at London's Rainbow Theatre and have sold over 100 million records worldwide.