What: Keith Greeninger and Dayan Kai

When: 7:30 p.m. Friday

Where: The Belfry, 302 E. Main Ave., Sisters

Cost: $20 plus fees in advance, $10 plus fees in advance for ages 18 and younger

Contact: sistersfolkfestival.org or 541-549-4979

Singer-songwriters Keith Greeninger and Dayan Kai have collaborated for close to 20 years, criss-crossing the United States and Canada and playing on each other’s albums.

In that time, they’ve realized something about their audiences, and themselves. As Kai put it in a recent conversation with GO! Magazine: “We’re tree-hugging dirt worshippers.”

“I’ve looked at this before. I think really it’s water people — people who are into water, whether it’s hard or soft water, frozen or otherwise,” Kai said from his home in Maui. “It seems like all the places that have really majestic nature, we seem to have kin in those places. So I think it’s the water and the nature, the mountains and the forests. We seem to have less huge followings in the bigger, more industrialized parts of the country, but that’s also probably because we’ve chosen to visit those places and been more attracted to those communities.”

So it’s not at all surprising that Central Oregon has been a frequent stop for Greeninger and Kai over the years, together and separately. The duo debuted at Sisters Folk Festival in 2004 and have returned many times since, with Greeninger becoming a regular instructor at the festival’s Americana Song Academy. The duo has also worked with the festival’s education program in Sisters schools, the Americana Project, and have produced and played on records by local songwriters Dennis McGregor and Anastacia Armstrong. They will return to Sisters, and SFF, to play The Belfry on Friday, their first show together in the city in about four years.

“I think there are these places where you cannot escape the landscape, so to speak — you can’t escape the mountains or the ocean,” Greeninger said from his home in Santa Cruz, California. “They influence you. They kind of dictate how much building you can do, and how much of this and that, and that’s a wonderful thing. I think we’re both drawn to those kind of places. Where you guys live is definitely one of those places where people in the community have made peace with where they live and the natural elements around them.”

Kai, who grew up bouncing between Hawaii and California, met Greeninger while still living in the Santa Cruz area. Their first recorded collaboration was on Greeninger’s second solo album, “Back to You,” in 2001, but the duo had met through a mutual friend at a bonfire and jam session Greeninger held at his home in the mountains.

“Dayan and his buddies finally showed up that night, and we just really, really connected well,” Greeninger said. “And I was literally heading out — in a few days; I had a tour booked on my own, and I invited him. … The age difference between Dayan and I — I think there’s maybe a 10- or 11-year age difference. At the time, when I first met Dayan, he was in his early 20s. It was great because I was already into my mid-30s at the time or whatever, and I was already touring, and I was saying to my wife, ‘It would be great to find some younger guys who just wanted the experience to get out on the road.’”

The two come from very different backgrounds. Blind since birth, Kai gravitated toward music early, and was taking classical piano lessons by the time he was 2. His father and grandmother were both musicians — his grandmother taught him his first chords on guitar and also figured out he has perfect pitch.

“I think I probably would have gravitated to music had I been able to see, although whether I would have been able to pursue it as a profession, I don’t know,” Kai said. “… There’s times when I’ve wished that I had something like construction to fall back on, but I don’t have that option. And so because of that, that I think certainly lit a fire under my butt to diversify my skills and be extremely valuable to certain musical situations.”

Greeninger, who is indeed a carpenter — he spent his youth traveling in the United States and Central America for work — didn’t pick up guitar until high school. A self-described jock, he focused on athletics as a kid, though he says music came naturally to him.

“Once that started, it just kind of took, but even then I was never like, ‘Oh, I want to do this for the rest of my life,’” Greeninger said. “It was just this thing that was so enjoyable for me — it was almost sacred. … When I look back on the course of my life, without knowing it, I guess I was actually already beginning to leave room in my life to be a writer and to be a musician.”

Greeninger made a name for himself in the 1990s playing alongside Kimball Hurd and Roger Feuer in the San Francisco-based City Folk. Kai learned to play just about every instrument imaginable, including piano, guitar, ukulele, woodwind instruments and drums, and did everything from commercial jingle-writing to recording engineering on top of releasing solo material. (Expect lots of instruments at the duo’s Belfry show, Kai said.)

Since 2001, Greeninger and Kai have been regulars on each other’s solo albums, in addition to releasing a duo album, “Make it Rain,” in 2010. Both artists have new albums in the pipeline, their firsts since Greeninger’s 2014 album, “Soul Connection,” and Kai’s 2013 album, “Resonate.”

“We don’t have a shtick. Even after all these years, we never really play something exactly the same,” Kai said. “It’s always inspired by where we are and the people that are around us. I think that’s what people keep coming back for.”