Tangerine Dream is a German electronic music group founded in 1967 by Edgar Froese. The band has undergone many personnel changes over the years, with Froese being the only continuous member. Klaus Schulze was briefly a member of an early lineup, but the most stable version of the group, during their influential mid-'70s period, was as a keyboard trio with Edgar Froese, Christopher Franke, and Peter Baumann. Early in the '80s, Johannes Schmoelling replaced Baumann, and this lineup, too, was stable and extremely productive. Without doubt, the recordings of Tangerine Dream have made the greatest impact on the widest variety of instrumental music during the '80s and '90s, ranging from the most atmospheric new age and space music to the harshest abrasions of electronic dance. The group has progressed through a full three dozen lineups and four distinct stages of development: the experimentalist minimalism of the late '60s and early '70s; stark sequencer trance during the mid-to late '70s, the group's most influential period; an organic form of instrumental music on their frequent film and studio work during the '80s; and, finally, a more propulsive dance style, which showed Tangerine Dream with a sound quite similar to their electronic inheritors in the field of dance music.