Complex sentence: It saw the group totally departing from the material that encompassed their past three albums, incorporating brass and string arrangements into their compositions at a point in which the group was experiencing personal issues, particularly related to Jim Morrison.
Split into simpler sentences: It saw the group totally departing from the material that encompassed their past three albums. The Doors incorporated brass and string arrangements into their compositions at a point in which the group was experiencing personal issues, particularly related to Jim Morrison.