Released in 1970 on the Bee Gees' album Cucumber Castle, 'Then You Left Me' stands as a defining example of the group's early transition from pop to soul-influenced rock. Recorded during a pivotal era in their career, the track showcases the brothers' signature harmonies and a more mature, emotive approach to songwriting that would characterize their later success. The recording features a driving rhythm section and vocal arrangements that blend R&B sensibilities with the emerging psychedelic rock sound of the late 1960s. While the song did not achieve the massive commercial chart dominance of their subsequent hits, it remains a significant song in their discography, demonstrating the band's evolving musical identity and their ability to craft sophisticated, emotionally resonant compositions that laid the groundwork for their future dominance in the disco and pop genres.