Complex sentence: Along with Bob Marley and Bunny Wailer he was one of the core members of the band The Wailers (1963--1974), after which he established himself as a successful solo artist and a promoter of Rastafari.
Split into simpler sentences: Along with Bob Marley and Bunny Wailer he was one of the core members of the band The Wailers (1963--1974). After which he established himself as a successful solo artist and a promoter of Rastafari.