From the moment Puff said it, it felt wrong. When the disgraced Bad Boy Entertainment founder rapped, on The Notorious B.I.G.’s “Mo Money Mo Problems,” that “ten years from now, we’ll still be on top,” it was in that flat preening monotone. Hip-hop’s commercial trajectory appeared to be such that he and his peers might keep accumulating yachts, but the dynasty he envisioned never seemed credible. By the time that song was finally released as a single, on July 15, 1997, Big had been dead for more than four months, and Puff’s Police-sampling elegy, “I’ll Be Missing You,” was already a No. 1 hit. In the video for “Mo Money,” when Puff raps the “ten years” line, he’s standing next to Mase in one of those glittering wind tunnels; they flit between different outfits and setups, their shimmying intercut with a team of dancers given slightly more robust choreography. Eventually we see archival footage of Big, presented with all the care and solemnity of the Terminator 2 clips that play as you wait in line at Universal Studios.

Big’s assassination left a vacuum in New York hip-hop. Jay-Z and DMX would move to fill it, each succeeding in different ways; even with the Wu-Tang momentum waning, Ghostface was regrouping to prepare for Supreme Clientele; Big Pun was getting acrobatic; underneath all of this, Zev Love X had reemerged, rapping with stockings over his face at the Nuyorican Poets Café as MF DOOM. At every strata, in little venues with sticky floors and yawning boardrooms alike, artists seemed to be competing not only for commercial supremacy, but for the right to drag the genre, and the city, in the creative direction they saw fit.

One week after “Mo Money Mo Problems” was issued to radio, Company Flow’s Funcrusher Plus became the first release from an independent label called Rawkus Records. The trio, comprised of rapper-producers El-P and Bigg Jus and DJ Mr. Len, had sold more than 30,000 copies of their 1995 vinyl-only EP Funcrusher without any label support; when Rawkus founders Jarret Myer and Brian Brater approached them with the financial backing of their friend James Murdoch—he of those Murdochs, the Murdoch Murdochs—they felt they’d have the creative latitude they needed to expand Funcrusher into something even more bludgeoning and unsettling. The expanded album opens with a too-sly extended joke about child molestation, then a quip about 2Pac being shot at Quad Studios in 1994 (this being less than a year after Pac was eventually killed in Las Vegas). Funcrusher Plus is often brooding and brutal, El-P’s production ingenious and totalizing. While the majority of its verses are de rigueur battle raps, the album sounds like one particularly grim vision of the future.

Over the course of 1997, Company Flow became a minor sensation, its singles fixtures on late-night radio, its cassette passed furtively around college campuses. It signaled something serious and subterranean—something El-P would go on to articulate even more fully, and more apocalyptically through his own indie imprint, Definitive Jux—but it was too knotty, caustic, and unconcerned with biographical mythmaking to mount a serious challenge to the then shiny-suit status quo. For that, Myer, Brater, and Murdoch would turn to someone far more assured of his own place in a hip-hop lineage.

Before he signed to Rawkus, Mos Def had appeared on Stakes Is High, the 1996 De La Soul album that became a sort of talisman of classicist revivalism. Through his own solo debut, 1997’s “Universal Magnetic,” and his other appearances on Soundbombing, Rawkus’ compilation mixtape from the same year, he immediately established himself as the can’t-miss talent from his generation: technically virtuosic but defiantly syncretic, weaving threads of hip-hop culture from the early ’80s into something bold and poetic and rhythmically inventive. (As with Big, there is literally no evidence of Mos, now Yasiin Bey, being less than a masterful musician: from the earliest demos, the syllables fall just so.) So when, in 1998, Rawkus issued his joint album with another Brooklyn MC, Mos Def & Talib Kweli Are Black Star, it was an actual gauntlet thrown.

Black Star was released on the same day, in September of that year, as Jay’s Vol. 2… Hard Knock Life and A Tribe Called Quest’s The Love Movement (and, down in Atlanta, OutKast’s Aquemini). “Definition” and “Respiration” were not going to vie with “Money Cash Hoes” and “Can I Get A…” for airtime on Hot 97, but Rawkus’ new distribution deal with industry giant Priority—combined with the underground rallying around Mos as its next great hope—made it sincerely impactful.

It was also cast, for reasons both in and out of its control, as a direct, even militant counterpoint to the Jays and Puffs of the world. In a 2011 interview with Pitchfork, Questlove remembers an edition of the vaunted Lyricist Lounge performance series from 1997, in which Mos rapped his version of Slick Rick’s “Children’s Story,” which would eventually appear on Black Star. Where Rick’s original was a pulp-crime classic, Mos turned the song into a parable: The transparent Puff stand-in, bastardizing the artform for profit, ends up riddled with bullets. Questlove recalls whooping, hollering, high-fiving the friends he was with; he also recalls Puff, “14 deep with dudes dressed in all-black,” glowering at him from the periphery.

So when Rawkus was preparing to release Soundbombing II in May 1999, a little over two years after Big’s death, there were clear battle lines, even though fatigue had set in on both sides of the culture war. The Bad Boy heyday had given way to something slightly more rugged, but there was no serious thought that Mos and company were going to supplant Jay-Z; some rappers on the more commercial side were even frustrated they had been cordoned off from the underground rappers they thought of as friends and peers. (Less than a half-decade later, Jay himself would rap wistfully about the alternate path where he became Talib Kweli.) Though showily brilliant in many places, Soundbombing II is not a campaign platform; it doesn’t prescribe a roadmap for the future of hip-hop. It feels, to mix metaphors the way its contributors do so deftly, more like a life raft, the last scrap of context in which their particular skill sets make sense. As the millennium drew to a close, so too did a whole school of hip-hop, its most eager practitioners lining up to freeze themselves in time.

Oddly enough for a record (and label) so self-consciously New York, the genesis of Soundbombing II was in Los Angeles. It was there that J Rocc and DJ Babu of the legendary Orange County-founded DJ crew the Beat Junkies were working at a Fat Beats location frequented by Mos and Kweli. Soon they asked the pair to take over for DJ Evil Dee of Da Beatminerz, who had helmed the original Soundbombing.

In the past quarter-century, the popular understanding of the album/mixtape distinction has evolved and then disappeared. What were first DJ-driven ventures and showcases for emerging artists became opportunities for major rappers to circumvent their labels; today it is a nominal divide at best, the mixtape designation used to lower expectations and artificially lengthen contractual obligations. But Babu and J Rocc took their assignment literally, adding scratches throughout, blending songs into one another, and filling out the tape with intros that make it feel like one ever-evolving track. Even if Babu and J Rocc weren’t the ones to broker the relationships, their deployment of spoken interludes from Prince Paul and Q-Tip is expert, signaling not just a spiritual but a literal line back to the Native Tongues movement, New York’s last great aesthetic and philosophical counterpoint to mainstream rap.

Yet it’s crucial to note that with Soundbombing II, Rawkus did not try to recreate 3 Feet High and Rising. There is without question a true-school, show-and-prove ethos that can be easily traced back to recorded rap’s beginnings, but little here scans as nostalgia or revivalism. Nor did Rawkus ask El-P to furnish this cast of MCs with beats that sounded like an extension of Funcrusher Plus’s dystopia. Even if you project onto the battle raps a specific enemy—Jay, Puff, Lyor Cohen—the broader point seems to be one of refinement, of craft, of practice. These are superbly competent craftsmen over beats that could have been made any time between 36 Chambers and Get Rich or Die Tryin’; they burrow deeper and deeper into grooves that would soon be abandoned, filled in, paved over by genre and industry that was changing rapidly. If there’s something quixotic about that, no one told R.A. the Rugged Man.

While Soundbombing II is a true compilation—a handful of songs are pulled from prior, smaller releases, or would appear on subsequent LPs—Mos Def’s verses provide something of a spine. On the Posdnous-produced “Crosstown Beef,” Mos teams with his younger brother, DCQ, to weave a story about a shooting outside a nightclub that’s full of uncommon texture: the expansiveness of an emptyish parking garage, the hue of the tints on a menacing car’s windows. On that song, even after shots ring out, Mos is poised, as if all of this is preordained. But when he opens the High & Mighty’s “B-Boy Document ‘99,” he whips himself into a frenzy—to the point where, by his verse’s end, he’s offering something of a mission statement for Rawkus, and for the movement it hoped to represent:

Don’t know what your label telling you
Or what magic beans they selling you
I can flow, you can’t though, example
Of a cat who just a modern-day Sambo
Who be bitching out to A&R demands so
You can collect your little petty cash advance, ho
You knock-kneed and sloppy, but not me
I’m I-N-D-E-P-E-N-D-E-N-T

Soundbombing II is not always so righteous. There are points at which the album teeters on the brink of self-parody. Pharoahe Monch opens “WWIII” by rapping “Cleverly beginnin’ ‘em with synonyms when I went in with homonyms”; El-P’s Howard Zinn-ass verse on “Patriotism” (“Indelible NATO force hidden agenda, puppet governments/I’m lovin’ it!”) is the kind of thing that gets passed around high schools like a sort of dial-up Rosetta Stone. But in both these instances, and others throughout the record, the rappers retain the charm that comes from expertise and enthusiasm. The warnings about hormone-injected dairy products are delivered with just enough acid to feel dangerous.

Silly as that single bar stripped from context reads, Monch emerges on Soundbombing II as a major force. After ending his three-album run as half of Organized Konfusion (the apex of which was the 1994 masterpiece Stress: The Extinction Agenda), Monch signed with Rawkus and got to work on his razor-toothed solo debut, Internal Affairs, which would be released later in ’99. While he ends up acquitting himself well on “WWIII,” Monch steals the entire LP with “Mayor,” his breathless yarn from the perspective of a cop who gets close to the mayor just to assassinate him.

“Mayor” was produced by Lee Stone and is built around the same Lamont Dozier sample that RZA would flip for Ghostface’s “Saturday Nite” the following year. While there is not a consistent palette from which all the producers on Soundbombing II draw, the standout beats are unforgettable: Capital the Crime Lord’s punishing slink for “Stanley Kubrick,” DJ Spinna’s glitchy fugue on “7XL.” On “When It Pours It Rains,” Diamond D turns one of the downbeat parts of the Rocky score into a wonderfully, typically understated bounce.

The cameo from Prince Paul, who was already a legendary producer before helming De La Soul’s first three albums, signaled a connection to the Native Tongues—the movement that strove, in the early ‘90s, to make New York rap jazzier, more colorful, and more Afrocentric. In a similar way, Kid Capri’s appearance on the intro to “Crosstown Beef” positions the Rawkus crew as natural successors to a more monocultural post in New York rap—that which would be inescapable on radio mix shows, on Canal St., out of aftermarket car stereos.

And while the record represents (or was made to represent) a specific point of view on hip-hop as a culture and industry in 1999, it articulates that view through such a variety of vocal styles that it begins to feel nearly comprehensive of what was happening in New York at the moment. To hear this, one needs only to contrast the silkiness of “When It Pours” with “Brooklyn Hard Rock,” where Thirstin Howl III raps as if every line ends with an exclamation point.

Babu and J Rocc give Soundbombing II a natural shape, sequencing concentric arcs of pacing and rhythm that underscore longer, thematic ones. The gritted teeth of the opening third slowly slacken to allow for more eccentric iterations of the same styles. One of the album’s few detectable commercial concessions comes right at the top. Eminem’s “Any Man,” which had been previously circulated as part of a demo and then had its verses meted out as radio freestyles, all designed to showcase his corrupted-cartoon imagery and elastic rhyming style. The song could have easily slotted onto The Slim Shady LP, which was released in February ‘99 and put Em immediately on the conveyor belt to superstardom. A year later, on The Marshall Mathers LP’s “Stan,” a mark of the titular fan’s obsession is his knowing “the shit you did with Rawkus.” Professed rap nerd though he is, once Eminem crossed the threshold onto TRL and interest-group pamphlets, he couldn’t go back; the barrier was not a permeable one.

Here you could say something trite like “Time marches on,” but that’s sort of the opposite of what Soundbombing II argues. Back in 1993, near the end of Tribe’s Midnight Marauders, Q-Tip relays some advice: “My man Extra P said, ‘Don’t say the years.’” That note, from the producer Large Professor, was about posterity—hip-hop was supposed to be “eternal,” not tethered to the moment. Soundbombing II’s lead single shirks this idea. “1-9-9-9,” which pairs Common with Brand Nubian’s Sadat X, settles into a midtempo, but something roils underneath. “Holding liquor in despair,” Com raps:

Gang signs in the air
I shine in spaces where time is just a glare
Hold the mic like a memory.

The scratched hook—punctuated by Chuck D’s booming, disembodied voice—is simply the year, one digit at a time, explicated and inescapable.

A little over a half-decade later, toward the final moments of Late Registration, Kanye West interpolates that song, which was no doubt burned into his brain as a fan-turned-collaborator of Common. He’s recounting his past, and that year—the one… nine… nine… nine…—is made to sound like ancient history. Because of course it is. In the early 2000s, Mos had rejected whatever savior status had been thrust upon him; Kweli and Com had seen their careers revived by Kanye himself; Jay had retired; the balance of power in rap had shifted down to Atlanta; the CD sales that made a venture like Soundbombing worth it to Priority were about to crater.

Underground rap had splintered. It was no longer a unified counterpoint to a similarly monolithic mainstream. Instead, it deviated in specific ways—hyperpolitical like Immortal Technique, hyperpersonal like Slug, dipping into the avant-garde like Busdriver. Later in 1999, Rawkus would release not only a set of Company Flow instrumentals, but High & Mighty’s Home Field Advantage and then, separated by only one week in October, Internal Affairs and Mos Def’s Black on Both Sides. There could be no ambiguity: This was the most important independent label in hip-hop. By the time Soundbombing III was released three years later, the run had all but ended. But in a genre built on the ephemeral—did you hear what so-and-so said over a James Brown break last night?—a fleeting moment being captured so completely defies any reasonable expectation.