Final answer:
John Coltrane left the Miles Davis Quintet in 1960 to form his own band, which led to a significant evolution in his musical career and substantial contributions to jazz music.
Step-by-step explanation:
The renowned saxophonist John Coltrane left the Miles Davis Quintet in 1960 to pursue his own musical projects and eventually form his own band. This marked a significant moment in jazz history, as Coltrane would go on to become a leading figure in the genre, with his own group pushing the boundaries of jazz music through innovative techniques and experimental sounds. His departure from Davis's group allowed him the creative freedom to explore and develop what would become his signature style, influencing generations of musicians to come.