Questlove remembers the exact moment when the Roots became passé. In Mo’ Meta Blues, the memoir he published last year, the renowned drummer, bandleader, producer, DJ, and all-around music geek flashes back to the filming of Michel Gondry’s concert film Dave Chappelle’s Block Party in 2004:

I remember one moment so clearly that it’s like it happened yesterday — more than that, it’s like it’s happening right now, and will continue to happen. We were shooting a performance of “Jesus Walks,” and Kanye wanted to come in with a marching band. I remember a welter of political and artistic thoughts crowding my mind. I thought about how presidential he looked and how black kids were responding to him, something I had never really focused on in our own audience. I remember having a kind of out-of-body experience and investigation of the thought of my own artistic death. “Am I dead already?” I wondered. It was a metaphor, but it wasn’t just a metaphor. A few years earlier, my mother had been driving on a mountain road in Pennsylvania when she lost control of the car. She rolled over six times, and for whatever reason — fate, God, luck — her body went out the window, perfectly, like a letter being delivered, just before the car crashed down into the woods. It was one of those near-death experiences when death was way too near. She told me that as she went down the embankment, her only thought was, “Oh, this is how it’s going to end.” She wasn’t panicked. She wasn’t even sad. It was more of a mix of resignation and realistic observation. I remember experiencing that same feeling the day of “Jesus Walks,” of thinking to myself, “Oh, I see. This is where I get off.” I saw the rest of the plot stretched out before me. Kanye was going to be the new leader, and I was fine with that.

Sounds about right. Throughout the first act of their career, the Roots’ live band approach to hip-hop seemed like something genuinely new. When I saw them in concert in 2003 on something called the Sprite Liquid Mix Tour (N.E.R.D., Talib Kweli, Robert Randolph and, um, O.A.R. were also on the bill), their live-band hip-hop revue seemed like the vanguard — “The Next Movement,” as they put it. They were a smart, catchy, unique hip-hop act with a powerhouse live show: What’s not to like? Still, by the time Kanye showed up with his Benz-and-backpack synthesis the following year, the neo-soul movement the Roots had helped foster instantly started to feel outdated. The next next movement had arrived, and from then on the Roots seemed confined to hip-hop’s periphery. They kept making records, some better than others, and Questlove remained in high demand for any number of musical endeavors, but the band was no longer near the center of the conversation like they’d been around the time of 1999’s Things Fall Apart and 2002’s Phrenology, the albums that yielded their biggest hits. I saw them in concert again in 2006, and while their show hadn’t changed much, the context around it was completely different. As Kanye was rapidly evolving past his signature pitched-up soul samples, the Roots seemed stuck. Worse, they seemed less and less like a rap group and more and more like a jam band; maybe O.A.R. hadn’t been such a strange tour pairing after all.

When the news broke that the Roots had signed on to be Jimmy Fallon’s house band on Late Night, it seemed like an odd pairing (this was before Fallon had proved his hip-hop bona fides and everyone thought of him as the guy who laughed too much on SNL) and possibly a gesture of defeat (here was a hard-touring original band leaving the road to play standards on late-night TV). I wondered if Black Thought, the group’s lead MC, was going to have anything to do in a TV show’s house band. I questioned whether they would be able to keep ties with Philadelphia, the city that spawned them. I worried that the Roots, after being conceptually marginalized in hip-hop, were literally sidelining themselves from the music business. At least they’d be getting paid, I figured.

Thankfully, the Roots and Fallon were a perfect match. He turned out to be a song-and-dance man with a youthful appreciation for music, and the Roots were goofier and better versed in comedy than anybody realized at the time. (Anecdote #17 here, with its references to human pyramids and Lorne Michaels trivia, is illuminating.) Rather than a death knell for the band, their gig on Late Night was revitalizing. Instead of falling into the jazzy/bloozy big band mold that had become the industry standard, they reinvented the the late-night house band into something forward-thinking and interactive. They wouldn’t be window dressing; they’d be an integral part of the show, combining with Fallon on musical comedy bits and collaborating with musicians of all sorts. Over five years, they became so essential to Fallon’s operation that when word came that he would be taking over The Tonight Show, the thought of him moving to L.A. and carrying on without his musical sidekicks was deflating. Fortunately, NBC was smart enough not to mess with a good thing; they moved The Tonight Show to New York and kept the Roots on board.

During that five-year stint, the Roots reinvented themselves as a band and reinserted themselves in the musical discourse. By signing on with Late Night, they essentially parked themselves at the center of the music universe. Just about every musician who matters passes through there eventually, and the Roots not only got to witness them all in action, hobnob, and learn some new tricks, they often got to collaborate, especially when rappers stopped by. They were suddenly involved in a large percentage of TV’s iconic music moments, be they historic (Tyler and Hodgy blowing the roof off, Frank Ocean tearing our hearts out) or just plain fun (the Miley a cappella, the Mariah Christmas sing-along). And they didn’t have to stop making records, cease touring completely, or cut ties with their hometown. It turned out to be an ideal situation for them.

The TV gig paid off big-time for the Roots in terms of exposure — how many viral videos have they been a part of in the past five years? — but it also catalyzed a new wave of creativity. The fresh environment on Fallon jolted them out of their routine and exposed them to an even vaster array of music. (Who could have imagined the Roots backing up Mark Kozelek on a 19-year-old Red House Painters song just because?) In the years since they joined up with Fallon, the Roots’ sound has evolved faster than ever, incorporating the likes of Jim James, Dirty Projectors, and Sufjan Stevens into their LPs without giving up their well-established identity. As Questlove explains in his book, the job security has freed them up to make the records they want to without worrying about keeping their label happy. They made an entire record with Elvis Costello, which wouldn’t have happened without the show. They’re in the spotlight to an unprecedented extent and at the peak of their powers — more well-rounded, better-rehearsed, and more widely known than ever.

The move was a game-changer for the Roots, but also for the institution of late-night TV. They brought fun and unpredictability to a venue that had become entrenched in its ways, clearing the way for all kinds of new possibilities down the line. It’s hard to imagine a late-night band featuring members of Les Savy Fav if not for the Roots first putting in work to make late-night TV hip. They have effectively vanquished Kevin Eubanks elevator music from the airwaves, and now, along with Fallon, they’ve taken over the most prominent perch in late night. Just as they had previously redefined what was possible in rap, they’ve rewritten the rules of music on TV. In a completely different context, they’ve become what they always claimed to be: The legendary foundation.