PORTLAND — Swedish folk trio Väsen has been bending the rules of traditional folk music for over two decades. Väsen’s music has, in some ways, the same spirit as the punk and anarchist movement here in the U.S. The sound is worlds apart, but it has similarly rebellious origins; initially some traditionalists in the Swedish folk music community objected to Väsen.

At 8 p.m. Tuesday, Oct. 14, they’re bringing that Swedish anarchist sound to One Longfellow Square. Väsen is comprised of Olov Johansson on nyckelharpa, Mikael Marin on viola and Roger Tallroth on guitar.

While Johansson and Marin were playing fairly straightforward folk duets, Tallroth’s guitar changed and challenged traditional Swedish music. These originally controversial guitar stylings are what allowed Väsen to attract an entirely new audience, increasing the band’s popularity to gain international reputation.

Doors open at 7 p.m. Tickets cost $20 in advance and $25 at the door. One Longfellow Square is at 181 State St. For more information, visit www.onelongfellowsquare.com.