Answer
**Hootenanny Singers,** a Swedish folk and pop music group, marked the beginning of Björn Ulvaeus's musical career. Formed in 1960, the band gained recognition for their upbeat melodies and humorous lyrics, achieving success in Sweden before Björn co-founded ABBA, a legendary pop and disco group, with Benny Andersson, Agnetha Fältskog, and Anni-Frid Lyngstad in 1972.