You couldn’t wrongfoot Jay-Z. That was the entire point of Jay-Z. By the fall of 1998, Jay-Z had become the biggest star in all of rap, and his haughty and unflappable demeanor was a huge part of the reason. As a musician, Jay had ventured beyond the borders of his native New York rap world, pulling flows and ideas from Southern rap, adjusting his delivery to fit whole new drum patterns. As a personality, he’d figured out how to project a sense of cold dominance, of showing that he could never be surprised. But then Jay-Z met a Mannie Fresh beat. And all of a sudden, Jay-Z sounded absolutely flummoxed.

In the fall of 1998, a 23-year-old rapper named Juvenile had erupted out of nowhere — or, more specifically, out of the CJ Peete housing projects in New Orleans — with a song so profoundly, overwhelmingly Southern that it felt like a transmission from some other, much funkier alien civilization. Over a beat that sounded like an evil robot’s spicy-food-before-bed nightmare, Juvenile, his New Orleans drawl a mile deep, mercilessly clowned some mysterious, all-pervading “you.” The “Ha” of the title wasn’t a laugh. It was a James Brown grunt, a simple verbal emphasis: “You brought our tape with a check, ha / You wearin’ a vest, ha / You tryin’ to protect your chest, ha.”

The song’s music video, from director Marc Klasfeld, turned Juvenile’s New Orleans into a whole world unto itself. It’s a visual tone poem, a meditation on snakes and boarded-up houses and above-ground graveyards and neon-color Porsches and ambulance lights and air-conditioner sweat and yellowing eyes. Juvenile wears crispy white clothes and stands in puddles, staring the camera down. The video shows such a collision of money and desolation that your brain can get whiplash just watching it. It’s fascinating and immersive and overwhelming, and it remains one of the best music videos ever made. For a while there, Rap City was playing it every single day.

The Jay-Z of 1998 had that same bloodhound sensibility that Drake has now — the power of knowing when a movement is cresting and realizing that he should get himself involved. With “Ha,” he got himself involved. The last song on 400 Degreez, Juvenile’s third album and the first record that his label Cash Money released as part of its deal with Universal, ended with a remix of “Ha” that featured Jay-Z. Jay was the first non-New Orleans artist ever to show up on a Cash Money track, and his voice immediately stood out, but not in the good way. On that “Ha” remix, Jay was clumsy and ungainly, sounding like a tourist trying to ask for directions while flipping through a foreign-language dictionary. He was lost. Unless I’m forgetting something, Jay wouldn’t show up on another Cash Money record until a decade later, when he and Lil Wayne made “Mr. Carter” together.

Cash Money was an army. That was the idea. The New Orleans label had been spending seven years developing by the time most of us got to hear what they were doing. In that time, they went from bounce music, New Orleans’ distinctly local form of chant-along dance music, to rap that simply sounded a lot like bounce music, adapting its cadences and catcalls. In that time, Cash Money became a sound, an aesthetic, a viewpoint, a visual sensibility, and maybe even a philosophy. Just as much as something like Wu-Tang, Cash Money came into the public eye fully-formed, a snowball already halfway down the mountain.

It’s not that we didn’t know how New Orleans sounded, or how it looked. By 1998, Master P’s No Limit had been a pop phenomenon for more than a year. I can still remember being totally baffled while watching I’m ‘Bout It, Master P’s unbelievably shitty straight-to-video smash, with a bunch of kids I worked with. They loved this movie, knew it well enough to quote it while watching it. And the next thing I knew, Master P was all over MTV, pushing a grimy and guttural version of Puff Daddy’s big-money flash.

Cash Money was merely the second big-money rap movement to emerge from New Orleans, but even after the shock of No Limit wore off, Cash Money felt different and dangerous. Master P was a first-order huckster, and he presented a gigantic roster of local acts like it was a comic-book universe. He saturated the market, releasing something new every few weeks. By contrast, Cash Money seemed stripped-down and urgent. There were only six rappers of any note, and they were all over each other’s songs. A few years later, we’d learn that Birdman was fucking all of them over financially, and many of them, Juvenile included, left the label contentiously shortly thereafter. But before we knew that — before they knew that — the young men of Cash Money came off as a one-for-all collective, a unified front.

And within that context, Juvenile stood out immediately. As Jay-Z would find out for himself, what Juvenile did was not easy. As young as he was, Juvenile rapped in a full-throated old-man croak. There was melody in that voice, a bluesy slither that found the notes in Mannie Fresh’s overwhelming snare-monsoons. He rapped with joyous energy and with urgent desperation, and he made them sound like the same thing. Even when he was in nihilistic fuck-the-world mode, there was bounce in his voice. He ate, slept, shit, and talked rap, and if he wasn’t a Hot Boy, then what do you call that?

Juvenile’s chemistry with Mannie Fresh, Cash Money’s in-house producer, was some De Niro/Scorsese shit. Fresh was a second-generation DJ and an innate experimentalist. All of the sounds on 400 Degreez are cheap and grimy — staggered 808 thwacks, plinky one-finger keyboard riffs, eerie horror-movie tones. And yet Mannie knew how to layer those things so that they’d sound orchestral. Like Timbaland before him, Mannie knew how to use music to reorganize space. But where Tim was a sci-fi visionary, Mannie was a deeply plugged-in localist crowd-pleaser, and you could always hear echoes of New Orleans second-line rhythms in the way he programmed his drum machines.

Precious few rappers could’ve made sense of those Mannie Fresh beats. (Maybe here we should credit Jay-Z with being the one non-New Orleans guy who was at least brave enough to try.) But Juvenile made those tracks feel like home. Mannie and Juvenile knew how to talk to each other; after all, Mannie had gotten Juve signed to Cash Money after hearing him rap at a bus stop. On 400 Degreez, Juvenile wrapped his voice around those tracks, navigating all the off-kilter pulses and panting blips. He made every line sound like a hook, and for those of us in coastal cities who had no idea what we were hearing, he made those beats make sense.

Juvenile and Mannie brought a whole team with them, too. There weren’t many rappers on Cash Money, and the ones who were there were at wildly different stages of their development. But they all sounded hungrily gifted. The first time most of us ever heard Lil Wayne was when he was doing the wobbledy-wobbledy ad-libs at the end of “Back That Azz Up”; somehow, Wayne was able build from there to the point where he became a transcendent generational star. And Mannie Fresh himself turned out to be a funny, gregarious, deeply entertaining rapper, a guy who knew how to use pauses for comedic effect: “MacGyver ain’t liver than a… Big Tymer / Big dick, a million dollars, and a… Pathfinder.”

In short order, we would learn a whole lot more about all these mysterious figures. They would all become stars, even if stardom wouldn’t last for most of them. And in the process, they broke rap open, establishing a national crossover audience for hyper-regionalized Southern underground rap music. A lot of that comes down to “Back That Azz Up,” the string-soaked party monster that was absolutely huge all through 1999. “Back That Azz Up” only made it to #19 on the Hot 100, but that song was everywhere, and it propelled 400 Degreez to four million copies sold within a year of its release.

In the 20 years since its release, rap music has internalized all these anarchic regional trends, and it’s harder for someone like Juvenile to come along and shock the world. But in the moment, that’s what he did. Juvenile was a compelling figure with a homegrown sound, a new-to-us accent, and a whole lot of urgency in his delivery. He made a great album, and he changed everything. Jay-Z had to catch up, and so did the rest of us.