Many, many bands have tried, but few have successfully captured the raw, elemental sound of pagan ritual. Träd, Gräs och Stenar remain pioneers in that regard, and the Swedish band’s wild, spontaneous jams are darker, earthier, and more hypnotic than virtually all other hippie music that came out of the 1960s counterculture movement.

The band arose out of a shape-shifting Swedish collective that released a series of albums under the names Pärson Sound, International Harvester, and Harvester; Träd, Gras och Stenar—it translates to “tree, grass, and stone”—was actually the musicians’ move toward the mainstream, and their 1970 debut under that name includes lengthy deconstructions of “All Along the Watchtower” and “(I Can’t Get No) Satisfaction.” But this music is still the polar opposite of accessible, full of drones and meandering instrumental explorations that evoke, at various points, lazy summer days, midwinter bonfires, and slowly shifting continents. The band broke up in 1972 but has reunited several times over the years, with members old and new.

Most recently, an outfit centered around guitarist Jakob Sjöholm and featuring Dungen’s Reine Fiske on lead guitar released an album under the modified moniker Träden, playing several live shows under that name as well. The sound was more polished and modern, but its trancelike gravitational pull was just as strong. Now Träd, Gräs och Stenar—using the band’s original name once again—is playing a few more shows in the US, including a rare date in Portland. It has every indication of being the most psychedelic event of the year.