In 1934, a former Mormon missionary turned anthropologist named Kilton Stewart stumbled upon the Senoi, a Pygmy tribe cloistered on a lonely mountain peak on the Malay Peninsula. As he wrote in his book Pygmies And Dream Giants, Stewart was on a quest to find the "universal man." Upon encountering tribes, he would subject them to fledgling cognitive tests, like Goodenough's Draw-A-Person test. In his few weeks among the Senoi, he came to the conclusion that their society was nonviolent as a result of their close connection to the realm of dreams, their expression and interpretation.

"According to the Senoi, pleasurable dreams, such as of flying or sexual love, should be continued until they arrive at a resolution which, on awakening, leaves one with something of beauty or use to the group," Stewart wrote. "For example, one should arrive somewhere when he flies, meet the beings there, hear their music, see their designs, their dances, and learn their useful knowledge." Stewart's notion of Senoi Dream Theory made its way back to The West, and dream discussion groups have proliferated ever since.

American trumpeter and composer Jon Hassell was taken with the idea of Senoi Dream Theory. On his 1981 album, Dream Theory In Malaya, he transposed it to the neighboring Semelai tribe, located not in the mountains but in the largest swamplands of Malaya. Using a field recording of the tribe's water splashing, Hassell wrote in the notes that their "joy-filled watersplash rhythm… [became] the generating force… and thematic guide for the entire recording."

Subtitled Fourth World Volume Two, it followed on Fourth World Vol. 1 - Possible Musics, his successful collaboration with Brian Eno from the year before, and codified his Fourth World aesthetic. Drawing on minimalism, electronics, ethnographic recordings and his own background, Hassell presented a sensuous amalgam of sound, taking a strand of music from an indigenous culture and allowing it to form the mutant combination of ancient and futuristic that has been Hassell's métier since the late '70s. Hassell described it as music from "unknown and imaginary regions."

"In those days, the Cold War days, there was the First World and basically the unspoken Second, which was the Soviet empire," Hassell once explained to an interviewer. "Anything outside of those two was called Third World, and it usually meant less developed countries. And those less developed countries were places where tradition was still alive and spirituality was inherent in their musical output, for lack of a better term. [Fourth World] was like '3 +1.' The idea was the merging of the traditional and spiritual side from the Third World with the First World technology, using the harmonizer and that kind of thing."

"Hassell's idea was pretty singular," Andrew Field-Pickering, AKA Maxmillion Dunbar of Beautiful Swimmers, told Truants when he delivered an all-Hassell mix back in 2012. "As we become more global as a people all things begin to seep out and inform each other, little snatches of online rhythm can inspire you very quickly, maybe he was just kind of clairvoyant about everything eventually blending and got to it early."

40 years after his debut album, Vernal Equinox, Hassell's Fourth World aesthetic has infiltrated the furthest reaches of electronic music. He's in the swampy repetition of Ricardo Villalobos, the muggy moments of Call Super, the morphing electronics of Oneohtrix Point Never and Arca, the peculiar sonorities of Jan Jelinek. In the past year, strands of Hassell's music appeared in some of the headiest new acts out there: Visible Cloaks, Don't DJ, Andrew Pekler, the Wah Wah Wino crew, NYC's Georgia and Montreal's RAMZi, to name just a few. Reissue labels—RVNG Intl., Music From Memory, Palto Flats, Emotional Rescue—have also explored the nexus of electronic and ethnographic sounds, from the works of forgotten artists like K. Leimer and Roberto Musci, Mariah's Utakata No Hibi or Sons Of Arqa. Last month, Optimo released Miracle Steps: Music From The Fourth World 1983-2017, a hefty compilation drawing a through-line from Mexican new age mystic Jorge Reyes to '80s post-punks like Rapoon and O Yuki Conjugate, conservatory composers like Larry Chernicoff to contemporary bedroom producers like Iona Fortune and X.Y.R. Listen closely and the Fourth World now pervades our modern world.

"It has been brewing and building for a few years in an almost morphic resonance and then quite quickly has reached critical mass," JD Twitch of Optimo said of Miracle Steps, which he compiled with fellow DJ and Fourth World enthusiast Fergus Clark. "The timeless nature of it and the fact it is quite hard to pin a lot of the music to the particular time it was made is a factor. It's primal, but also often hi-tech and evocative of an imaginary other. I think it is also partly due to the completely messed up times we live in and a need to mentally escape from time to time into musical dreamworlds."

Hassell was not the first to discover this new world. His mentor, Karlheinz Stockhausen, released compositions like 1966's Telemusik and his magnum opus, Hymnen, which processed and collaged snatches of national anthems from around the world and reconfigured them into a Pangaea of sound. Jazz musicians also trekked outside their hemispheres in search of new timbres. Jazz clarinetist Tony Scott dug the sitar and Japanese bamboo flute on Music For Zen Meditation. Alice Coltrane melded Indian timbres on classics like Journey In Satchidananda, then went further a few years later by setting ancient Indian bhajans into African-American gospel settings on her legendary ashram tapes. And then there's trumpeter Don Cherry, who helped revolutionize jazz in the late '50s as a member of Ornette Coleman's quartet. By the end of the '60s, he'd set about traveling the world, and his albums in the '70s absorbed a wide range of flavors: Javanese gamelan, Arabic reeds, Indian tambura and tabla, and much more.

"Don Cherry was a hero and a teacher of mine," the composer Larry Chernicoff told me via email. Like his mentor, Chernicoff's music touches on free jazz and gamelan, and his 1983 album Gallery Of Air, is something of a lost classic. "Woodstock, New York" (which appears on Miracle Steps) is one of the set's most driving pieces, powered by the furious patterns of African bow harps and flares of free jazz horns.

"In addition to everything else Cherry did musically, he played the large West African doussin gouni, a stringed instrument," Chernicof said. "My good friend Tom Schmidt and I picked up smaller versions and we always considered playing them to be a form of meditation. African stringed instruments lend themselves very much to that sort of trance. You have to get in the zone to play repetitive figures like we played on 'Woodstock, New York' for long periods of time, keeping the rhythm steady while making minute variations."

Chernicoff admits he doesn't think of his work as being Fourth World—he's not even familiar with Hassell's music—but he was happy to be part of Miracle Steps. "I was surprised that Fergus and Keith chose it for the comp. But you know what? You never know how these things are going to hit people when you record and release them." Nearly 35 years on, "Woodstock, New York" sounds right on time, its mix of spiritual jazz, minimalism and African music not beholden to any one state.

"For my own music, I'm generally aiming for this plausible-yet-unreal state," Andrew Pekler said of the processes that led to his album from last year, Tristes Tropiques. When I asked if Hassell was an influence on his own work, he recalled working in a record store and being struck by Hassell's Dream Theory In Malaya. He could hear strands of jazz, new age, electronic, organic instrumentation and the types of field recordings that could be found on renowned world music labels like Folkways and Ocora. He wondered where to file it at the shop.

"[Hassell] presents without obfuscation the musical and stylistic components involved and brings them into correspondence by applying the same processes to them all," Pekler said. "You always hear what is being transformed and how; nothing is rendered completely unrecognizable."

But it's a fine line to walk, not falling into kitsch or the blatant exploitation of the exotica trend of the 1950s (and its peculiar revival in the '90s), or to just be ambient music with some tribal sounds sprinkled on top. That sense of the unrecognizable stretches back to when Hassell's records first wafted out into the world, catching the attention of early industrial artists O Yuki Conjugate, who formed in 1982 in Nottingham, England.

"We were inspired by the Cabs [Cabaret Voltaire] and Jon Hassell simultaneously," band-member Andrew Hulme recalled. "Eno and Hassell's work from that time was astonishing and changed the landscape for us. What they did was to suggest other worlds and landscapes with the music and to listen in a deeper way, to immerse yourself in it."

Bandmate Roger Horberry felt that their early efforts were failed attempts to replicate Hassell's soundworld, but that such failure resulted in their own peculiar take on industrial, post-punk and the sounds they heard in ethnographic recordings. "When you're not a musician it's about being creative with what you have around you," Horberry said. "We weren't interested in guitar and bass. Because we listened to Hassell's trumpet playing, we roped in my girlfriend at the time, Clare, who could play flute. We had a sawn-off beer barrel and dog bowls to play percussion."

For post-punks in search of something beyond punk, for industrial acts interested in trance-inducing percussion, there was an embrace of indigenous folk forms and an attempt to fold mbira and homemade percussion into their own songs. "I've always found an edge to Fourth World that was lacking in that other stuff," Hulme said. "It's not just light, pleasant, meditation-type music like new age, or kitsch like exotica. There's a darker side to it. I think Fourth World is trying to go deeper into the psyche by evoking images and imaginary landscapes."

Decades on, even a new project like Portland's Visible Cloaks finds sonic terrain on the Fourth World still worth exploring. On their latest album, Reassemblage, they take DNA from the likes of Japanese pop act Dip In The Pool and a "digital analysis of Aka pygmy vocal music," twisting them into crystalline new structures. "It's an investigation of the blurring of cultural signifiers and what the implications of this process might be, to think about what kind of meaning you are left with within this space that is simultaneously everywhere and nowhere," band member Spencer Doran explained.

Doran also perceives a darker side of such cultural sampling. "There is something in the artificiality of this imagined space that both compels and confuses me," he said. "Cultural fusion is a really prickly topic… the way it spilled out into pop culture in the '90s (and beyond) spoke more to homogeneity, exploitation, other-ing—a form of distance that ironically parrots the colonialist dynamic that it was intended to unravel. It's all very intentionally disorienting, bringing up questions about identity and how it is shifting in global culture."

It even reflects back on the current state of pop music, wherein a once localized sound spreads like wildfire, or, disregarding boundaries, like a virus. Almost any native sound is up for grabs for anyone around the world: Auto-Tune sweeps across Africa weeks after its advent in the West, the Caribbean riddims of soca and dancehall are cast as pillowy things by tropical house producers in Scandinavia, and Nigerian Afrobeats find their way to the pasty pipes of Ed Sheeran. What has Jon Hassell wrought?

A few years ago, on a debilitatingly hot day in Los Angeles, I paid a visit to Jon Hassell, who has a low-key house on the west side of the city, a few miles from the Pacific Ocean. We sat in his backyard and chatted as Hassell let the garden hose run uninterrupted, creating shallow pools for his two dogs to lap at and giving LA's dry desert air a muggy feel. It was as if Hassell's presence made his surroundings a bit more like a jungle than a suburban yard.

More recently, we chatted about the sudden uptick of interest in his music. In addition to Optimo's Miracle Steps compilation, which features Hassell's thundering drum piece of that name as the central track, he also recently appeared on Tresor's Dreamy Harbor compilation, placing the octogenarian in the company of Terrence Dixon, Donato Dozzy, Juan Atkins and Moritz Von Oswald. Later this year, he'll release a new album called Pentimento, the first release on his Warp Records sub-label, Ndeya.

When I called, Hassell was hanging a portrait of Guy Debord from 1962 in his home studio. He marveled at the similarity between the French Situationist and famed earth artist Walter De Maria (who also was drummer in the pre-Velvet Underground group the Primitives). Hassell says that Debord was "the first one to blow the whistle on the society of the spectacle, of which Trump is now the reigning emperor." There's a collage on his wall that he says will serve as part of the artwork for the new album.

Hassell's seen first-hand some of the 20th century's most profound paradigm shifts in music. Born and raised in Memphis, he spent time in juke joints as the segregated city began to slowly mingle blacks and whites, giving rise to musical melting pots like the city's famous Stax label. In the 1960s, he studied with Karlheinz Stockhausen in Cologne, where his classmates included future Can members Holger Czukay and Irmin Schmidt. When he came back to the States, he found himself playing in Terry Riley's ensemble as they recorded the minimalist masterpiece In C. In the '70s, he premiered his groundbreaking pieces at The Kitchen alongside the likes of Arthur Russell and Rhys Chatham.

"Hassell's was a music I felt I'd been waiting for," said Brian Eno, who encountered Hassell's music in the late '70s. It's easy to hear how his gravity affected Eno's post-glam trajectory. Hassell contributed to Talking Heads' Remain In Light and Peter Gabriel and David Sylvian's forays into world music in the 1980s. He was also invited to work with Eno and David Byrne on My Life In The Bush Of Ghosts, though the two rock stars ultimately struck out on their own. (Hassell says that album contains "a distinct borrowing" of his own style.)

Hassell's music through the next decade was heady, drawing on indigenous sounds but also showing him to be an early adapter of sampling technology. "I would often be able to segue between anything with a Hassell record," Field-Pickering said of playing Hassell's albums on his Future Times radio show for NTS. "It's really open music."

Jon Hassel

"The coupling of two realities, reconcilable in appearance, upon a plane which apparently does not suit them" is how the surrealist Max Ernst described his approach to collage, an approach that informed Hassell as well. "When I was doing the last record [2009's Last Night the Moon Came Dropping Its Clothes In The Street], I had on my wall this big sign that said 'I want surreal, not earnest,'" Hassell said with a laugh. "'Ordinary things in a strange atmosphere, or strange things in an ordinary atmosphere.' Yeah, no doubt, surrealism's a facet."

To this day, Hassell still raves about the electrified music of Miles Davis and the sambas of Antonio Carlos Jobim and João Gilberto. "Brazilian music, there's always something there in that culture that is very sexy, that gets to the primacy of their music," he said. "Fourth World—or any of the other ideas I've been promoting—they're all basically cloaked in one basic idea and that's the primacy of the female."

Talk quickly moved to primeval man's worship of women and the hyper-masculine players currently on the world stage, before Hassell shifted to the music of the pygmies made in the Ituri forest in the Congo, which began to make its way out of the forest thanks to field recordings made in the mid-20th century. To Hassell's ears, it remains some of the most mirthful and idealized social music on earth. "It was just a model of the best of everything in a sense," he said. "You had old people and young people dancing and singing and making this incredible music. I was like, this is a model for a perfect society, in a way, you know, that extrapolation from the sheer joy of the music itself and the complete uniqueness of it."

"You're hearing this music coming from… not very far away, but somewhat far away," he said of recordings made in the depths of the Ituri forest. "As far as using a little digital slice of something and turning it into another piece of music… it's like taking a tile and making a mosaic out of it. In the new geography created by our media world, these pre-media cultures function as the elements do in chemistry, providing the relatively pure building blocks for the new compounds."

That love of non-Western music presented a problem for a Western composer with a "fascination with, or love of a particular sort of ethnic thing," Hassell said. "What do you do with that idea? You can't become Indian, right? You can't become Tibeten. And so what could you do?"

Hassell credits the father of minimalism, La Monte Young, with introducing him to a new concept of conceiving and hearing music. "Horizontal music is like what happens next, which is 99.9% of most music," Hassell explained. Downing hashish milkshakes to get deeper into the drones that Young and Marian Zazeela conceived, Hassell began to understand the stoned notion of vertical listening. "You discover this world of overtones that's happening on top of everything." He compares it to legendary Californian visual artist Robert Irwin, whose minimal paintings and installations are austere to the point of being barely perceptible. "Perceiving yourself perceiving," is how Irwin put it. Playing with Young and Zazeela, Hassell became acutely aware of "listening to yourself listening."

Between the vertical and horizontal, Hassell struck out for a diagonal, a music that could hover in place yet delve deep into the interior space of a sound. There are thundering rhythms that defy gravity, melodies that curl tighter rather than unfurl in linear fashion. Go through his catalog and his trumpet becomes a phantasmagorical thing, something that transcends language, both unheard yet uncannily familiar. It's a canopy of tropical birds, a woman's plaint in a foreign tongue, a buzzing insect, a Bedouin horn calling across the dunes, the distant whistle of a train, Chet Baker on Venus, an alien gurgle here on earth.

So how does the visionary musician see this new generation of artists similarly entranced by the Fourth World? "I'm very heartened by that," Hassell said, though he wondered about what that influence actually means in our present moment. "Now we're in digital la-la-land, taking a millisecond or a few milliseconds of something that's in the digital domain, and making it into something else… there is no original anymore. You've got a copy of a copy of copy of a copy."

"It's not that he created something outright musically, but that he put a lot of emerging technologies and sounds together in a way that was ahead of his time," Field-Pickering said of Hassell's music. "There's a little bit of Hassell's vibe that goes against that Smithsonianized sort of music worldview that a lot of people like me grew up jamming. Hassell's stuff is way more wild. I feel like it expanded forever with the internet."

As the internet continues to absorb and entangle all cultures, it makes sense that Hassell's hybrid would resonate for a new generation of music-makers prone to eschewing categorization and genre tags. For those who want to make electronic music and not wind up as simply house, techno, new age or ambient, Fourth World is a way to elude categorization. "Fourth World is a view point," Hassell said. "Out of which involves guidelines for finding balances between accumulated knowledge and the conditions created by new technologies."

Striking a precarious balance between the ancient and the modern, Fourth World speaks to our present moment, whether we seek to escape our world and plunge deeper into the imaginary or attempt to grasp a quickly evaporating past and its primitive wisdom. And no doubt there will soon come another technology that pushes its trailblazers and followers alike into another unknown, imaginary region.