For the past decade or so of their friendship, John Haughm and Don Anderson have indulged in the same activities many of us do: Taking in art films at independent theaters, or coffee and beers on Southeast Belmont. But unbeknownst to our waitress at the Horse Brass Pub a few weeks ago (who was wearing a Bright Eyes sweatshirt) the bar's patrons were in the presence of cultural heroes on a par with musicians like James Mercer or Colin Meloy. The two men in their late 20s are in no way local celebrities. Their band has never been covered by local press, and of the 17 shows Agalloch has played in its seven-year existence, only three have been in Portland, with a fourth planned for this Saturday, July 29, at Sabala's Mount Tabor. Still, Anderson and Haughm's folk-influenced metal band is one of Portland's greatest cultural exports, arguably the most respected Portland metal band ever, and roughly as well-known as the Decemberists internationally.

Since the release of their debut, Pale Folklore, in 1999, Agalloch has been a favorite of folk metal and black metal fans worldwide. Terrorizer, a U.K.-based metal magazine that features mega-bands like Metallica, called Agalloch "one of metal's best kept secrets," making them huge by underground standards. Anderson reports that about half of the hundreds of letters he gets from fans each year are from Europe or even South Africa, Brazil and Israel. Unlike bands that build a following geographically, starting with their hometown, Agalloch has caught on simply by word of mouth, dotting the entire globe with fans.

Familial obligations tie bassist Jason William Walton to home, and Anderson now spends most of his time as a graduate student and teacher in Bellingham, Wash., making touring almost impossible. But the group doesn't mind, pointing to the album as a better medium for its music: "I really have to work on each of our records," Anderson says, "and I think people can sense that I want it to be like good literature."

Although most Portlanders would never know it, this band is at the cutting edge of Scandinavian black metal—pushing the celebrated style to its limits. Agalloch's recordings are incredibly well-composed and rich in detail, demanding multiple listens. Anderson calls it music for the "headphones generation." His band's sound been been dubbed "grey metal" by others, a term Anderson says he "prefers over all others because it implies an overcast Northwest sky."

He's not being overdramatic, either. Portland and its surroundings set the scene for many of Agalloch's songs. Haughm claims that his songwriting is largely inspired by the natural surroundings of the Pacific Northwest (as well as films by directors like Ingmar Bergman and Alejandro Jodorowsky). Parts of Agalloch's latest, Ashes Against the Grain, were written by Haughm on Mount Hood, and the band's sophomore album, The Mantle, features photos of animal statues in Portland as well as "The Hawthorne Passage," a nine-minute instrumental meant to symbolize crossing the city.

Despite conceptual ties to the United States, Anderson says fans are often surprised to discover that Agalloch is American. The band's atmospheric (as opposed to virtuosic or melodic) approach is European, but when that approach is applied to a Northwest landscape, it gives Agalloch a sound that is likely to strike a first-time listener as unique and then obsession-worthy.

If there's any group that shares Agalloch's sound, or has obviously influenced them, it's the Norwegian band Ulver. The lyrics of Bergtatt, Ulver's 1994 debut, are based on Norse folklore, and while Haughm's lyrics aren't directly tied to specific legends, they are very much in a folkloric style. But Agalloch achieves something Ulver's work in metal never could. On Ashes' "Not Unlike the Waves," the band stretches its words through numerous measures, employing a slower pace than Ulver does and adding monastic harmonies to give the lines "Aurora swims in the ether/ Emerald fire scars the night sky"—which are already archaic in their diction—a tone of expansiveness that seems to belong to a less-busy, less-populated era.

While Ulver has exuberance and urgency, Agalloch keeps a very strong, clear beat in "Not Unlike the Waves," marked by drummer Chris Green's extraordinarily deep and liquid snare drum, which recalls the Finnish band Moonsorrow's most rhythmically driving moments. Agalloch exercises patience as it holds off before changing the rhythm. As the barely audible bass line doubles in speed to anticipate a transition, the song builds tension at an almost subconscious level.

This focus on tension couples with warbling, surf-influenced guitar lines on tracks like "Limbs" and "Fire Above, Ice Below," to suggest that Agalloch has recently taken a few cues from post-rock bands like Japan's Mono. Never relying on rage or anger, Agalloch has always been a metal band with a relatively broad emotional palette, as perhaps best shown by Haughm's stylized growling. Haughm's growl is not unlike some of the breathier moments in Attila Csihar's work with black metal pioneers Mayhem, but it is more controlled, somewhat like a very metal whisper.

Haughm uses that whisper to deliver devastating lines, as in "Falling Snow," a song about a man freezing to death on a mountain. All three of Agalloch's full-lengths focus on the theme of the relationship between man and nature, but Ashes, which Haughm says may be the last album to take up this theme, is more specifically concerned with man's destruction by nature. We are given a description of the scene surrounding a dying man rather than his sorrows, underscoring the anonymity and inevitability of his death: "The snow has fallen and raised this white mountain/ On which you will die and fade away in silence."

The music that accompanies this panorama is wrought with bright, looping guitar melodies that could pass for the heaviest moment on a Mogwai album, and in its simple, stoic power, seems to embody the force of nature. Despite its subject matter, "Falling Snow" isn't particularly dark or sad; it simply matches the steady strength of a blizzard, drawing, in theme and execution, attention to the frailty of man in this world.

Elements like Haughm's vocals create an underlying melancholy to Ashes, but Agalloch has allowed its grey metal to grow on a diet of post-rock, producing its least dark, yet most powerful album. "You can only go so far with pessimism and nihilism," Haughm says. "You risk becoming a parody of yourself if you fail to do something or say something new with them."

Agalloch performs Saturday, July 29, at Sabala's at Mt. Tabor with Waldteufel, Wolves in the Throne Room and Giant Squid. 9:30 pm. Cover. 21+.

Read a full interview with Agalloch on WW's