Sui Generis is one of the most influential rock bands in Argentine history, enjoying enormous success and popularity during the first half of the 1970s and a following that lasts to the present throughout South America. Its youthful songs, classical at sing-along gatherings, became hymns for successive generations of Argentines and are part of the national cultural landscape. Charly Garcia was author of most ot the songs and arrangements, which went from the simple folk style guitar, piano and flute (incorporating small elements of classical music, taking advantage of Garcia's conservatory training) of their greatest hits in the first and second album, to the more developed symphonic/prog rock of their last concept album. Sui Generis disbanded on September 5, 1975, in a mythical concert which was turned into a popular record and film, and, despite concerts that took place in 1980 and 2001, a permanent re-formation has been ruled out.

Source: Wikipedia (https://en.wikipedia.org/wiki/Sui_Generis)