Olov Johansson and Mikael Marin started playing together as teenagers around 1980. During the early 1980's they would regularly visit Curt and Ivar Tallroth and Eric Sahlström, older musicians who lived nearby in the Uppland region, where they would play and learn traditional music from them. In this way they became a link in the living tradition that Swedish folk music has enjoyed through the centuries.

In 1989, at a music gathering in Røros, Norway, Olov met Roger Tallroth and asked if he would like to try to jam on nyckelharpa and guitar for a bit. Roger declined, intent at that moment on taking a shower. Fortunately, the shower was occupied, so Roger returned with his guitar, and they played for the rest of the day and far into the night. Among the witnesses to this fateful jam session was Olle Paulsson, who thought it was the best music he had ever heard, and made a promise to start a record label if they were willing to be recorded for a CD (and thus Drone Music was born).

The following summer Olov became World Champion of both the modern chromatic and older historical nyckelharpas at the first-ever Nyckelharpa World Championships at Österbybruk, Sweden. The added momentum for the first CD recording, which was entitled "Olov Johansson: Väsen." Väsen is a Swedish word with many meanings: spirit, noise, a living being, essence among the most prominent. It was originally meant to just be an album title, but soon people were calling to book the band "Väsen" and the name stuck.

Initially some traditionalists (or something else, it wasn't many at all) in the Swedish folkmusic community showed some resistance to Väsen. While Olov and Mikael were playing fairly straightforward folkmusic duets, Roger's guitar definitely provided a different twist on Swedish traditional music. Yet it's exactly the guitar chordings and rhythms that also attracted an entirely new audience, and the band's popularity gradually grew, along with their international reputation.

In 1994, with two more studio albums under their belt ("Vilda Väsen" on Drone and "Essence" on the French Auvidis/Ethnic label), Väsen were asked to participate on a project of Swedish rock musician Mats Wester called "Nordman," which featured rock music and lyrics but with arrangements and playing by Väsen. The first Nordman CD was a huge hit in Sweden, and the band embarked on two tours and recorded a second Nordman CD, playing in front of audiences of up to 25,000 people. On the first Nordman tour they met drummer André Ferrari and eventually experimented with a drums-and-bass version of Väsen. Ultimately, they settled on André playing hand percussion, and the band officially became a quartet in 1996.

In 1997 the quartet recorded "Varldens Väsen" ("Whirled" in North America). Tours of Norway, Denmark, Finland, Italy, France, the United States and Canada followed, as did a Swedish Grammy and two appearances on the national radio program "A Prairie Home Companion" in the U.S. In 1999 the band released their sixth CD, "Gront." 1999 was also the year of the first Nordic Roots Festival in Minneapolis, Minnesota, U.S., an annual event which lasted ten years, of which Väsen was the most frequent featured artist. Their 2000 performance was released on CD as “Live at the Nordic Roots Festival.”

Meanwhile the members of the band were getting older, having babies and facing the challenges of being a musician in the modern age. A widespread U.S. tour in September 2001 had to be scrapped after 9/11. Although the tour was rescheduled for 2002, André's reluctance to tour and economics forced the band to decide to come over as the original trio. The success and pleasure of playing a new set of trio material culminated in two new recordings- “Trio” and “Keyed Up.” Ultimately, it also resulted in a sort of re-birth of the band, which to this day continues to be primarily a trio, although André joins for specific projects and gigs, especially in Sweden.

In 2004, Väsen were invited to Japan by Yoko Nozaki, their Japanese label (Music Plant) owner. This would be the first of many visits, one of which resulted in a live album (“Live in Japan”) in 2005. Japan is now a regular touring location for the band, along with the United States and much of northern Europe.

2006 brought an invitation to participate in the Carl Linnaeus tricentennial celebrations in Sweden, which became a project that included André and unearthed a surprising amount of music written specifically for the famed botanist. Väsen’s creative arrangements of these old tunes were performed at the celebrations in Uppsala, and recorded as “Linnaeus Väsen.”

Meanwhile, Väsen’s international fanbase continued to grow. The American “new acoustic musicians Mike Marshall and Darol Anger reached out for a collaboration, which resulted in a 2007 album and tour dates, and exposure to a new American audience. And a specific concentration of Väsen fans in Bloomington, Indiana, around the Lotus World Music & Arts Festival, managed to get the city to rename a city street during the festival as “Väsen Street.” This inspired a tune by Olov, which became the title track of their 2009 recording.

Punch Brothers, and American acoustic and “neo-bluegrass” band, recorded a cover of Mikael Marin’s “Flippen” in 2012 for their album “Who’s Feeling Young Now?” and it has become a staple of Punch Brothers’ live set, spreading the word further, globally. As a result, in many parts of the world, “Flippen” is mistaken as a traditional American bluegrass tune!

2013 saw the creation of a new set of mostly original Väsen tunes with the “Mindset” CD. A live performance of much of these tunes, along with some old favorites, was captured on video during the band’s celebratory 25th Anniversary tour at an old movie house in Örsundsbro, Sweden on 24 July, 2014, and subsequently released as a DVD/CD set. Later that year (25 October) the band was honored with a big “25 Jubilee” event in their “home town” of Uppsala, featuring many guest musicians.

When Michael League formed the band Snarky Puppy back in 2004, one of the first tunes the band tried to play together was André Ferrari’s “Shapons Vindaloo.” League’s admiration for Väsen ultimately lead him to invite the band to participate in the second Snarky Puppy Family Dinner in Feburary 2015, along with a host of other musicians including Becca Stevens, David Crosby, and Susana Baca. The resulting performances were recorded and released on audio and video.

2016 became a year of collaborations, from a one-off with the Danish String Quartet at the Savannah Music Festival, to a short tour with the Norwegian classical ensemble Trondheimsolistene (Trondheim Solists), and a more extensive touring project with Lena Willemark and the Norrbotten Big Band in Sweden (and once again, André Ferrari). In between, the trio played gigs in Sweden, Germany, Belgium, the U.S. and Japan.