Complex sentence: It referred to overlaps between politicised pacifist post-hippies, generally non-pacifist progressive rock fans and non-politicised Psychedelic music and Psychedelia fans, moving between rock festivals, free festivals, happenings and alternative society gatherings of various kinds.
Split into simpler sentences: It referred to overlaps between politicised pacifist post-hippies, generally non-political progressive rock fans, and non-political Psychedelic music and Psychedelia fans. The individuals moved between rock festivals, free festivals, happenings and alternative society gatherings of various kinds.