The Hootenanny Singers are a popular folk group from Västervik, Sweden, founded in 1961. The group included Björn Ulvaeus, who later became a member of ABBA. Other band members were Johan Karlberg (b. Karl Johan Hilding Karlberg, 14 April 1943, Vimmerby, Sweden d. 16 August 1992, Västervik, Sweden), Tonny Rooth (b. Sven Villy Tonny Rooth, 30 November 1943, Västervik, Sweden) and Hansi Schwarz (b. Hans Carl Schwarz, 16 March 1942, Munich, Germany d. 10 January 2013, Lund, Sweden). The group was named "The Northern Lights" for a US-released LP in 1966. Early debut.
https://en.wikipedia.org/wiki/Hootenanny_Singers