Two rappers on the rise to hip-hop stardom became fast friends — and even faster enemies, which may have led to their untimely passings.

Their worlds seemed destined to collide. They were two of the most talented hip-hop rappers on the scene. And they both were dedicated to exposing the truth of the tribulations of life on the streets, social injustice and the racial divide. But the biggest difference between Tupac Shakur and Biggie Smalls: They represented different coasts.

What exploded into arguably the biggest rivalry in music history, ended up in the death of both artists, just as their careers were skyrocketing. Tupac (also known as 2Pac) was gunned down on September 7, 1996, and died six days later, while Biggie (also known as the Notorious B.I.G.) was shot and killed six months later on March 9, 1997.

Neither murder has ever been solved.

But one thing that there’s no question about is that they started off as friends.

READ MORE: Inside Tupac's Last Days

Tupac entered the music scene two years before Biggie

Born in the Harlem neighborhood of New York City as Lesane Parish Crooks, Tupac’s single mother moved the family often in an attempt to escape the high-crime areas. They first went to Baltimore and then to Marin City, California. It was there that Tupac’s love and talent for poetry was bred. He eventually broke into the music business, first as a roadie and dancer for the group, Digital Underground. He eventually he took the mic in 1991, with his debut album, 2Pacalypse Now, released that year.

Meanwhile, back in New York City, Christopher “Biggie” Wallace, was raised in Brooklyn, spent his teen years attending prestigious high schools (where English was a strong subject), dealing drugs in the streets and rapping for fun. “It was fun just hearing myself on tape over beats,” he said in his biography for Arista Records.

But a demo he made found its way to Source magazine, which spotlighted the young talent — and he was soon represented by Sean “Diddy” Combs (also known as “Puffy Daddy”). His first single, “Party and Bulls**t” came out in 1993.

Tupac Shakur, Biggie Smalls and Puff Daddy perform onstage at the Palladium on July 23, 1993, in New York City

Tupac Shakur, Biggie Smalls and Puff Daddy perform onstage at the Palladium on July 23, 1993, in New York City

Biggie asked Tupac to be his manager

By that year, Tupac was already a platinum-selling artist, so Biggie asked a drug dealer to introduce him to Tupac at a Los Angeles party, according to a Vice excerpt of the book Original Gangstas: The Untold Story of Dr. Dre, Eazy-E, Ice Cube, Tupac Shakur, and the Birth of West Coast Rap by Ben Westhoff.

“'Pac walks into the kitchen and starts cooking for us. He's in the kitchen cooking some steaks,” an intern named Dan Smalls who worked with Biggie recalled of the meeting. “We were drinking and smoking and all of a sudden ‘Pac was like, ‘Yo, come get it.’ And we go into the kitchen and he had steaks, and French fries, and bread, and Kool‑Aid and we just sittin’ there eating and drinking and laughing...that's truly where Big and ‘Pac’s friendship started.”

There was mutual respect between the two, as well as their friend groups. According to the Vice excerpt, EDI Mean, a friend of Biggie’s, said, “We all thought he was a dope rapper.” The story reports that Tupac gave Biggie a Hennessy bottle as a gift. Biggie would crash on Tupac’s couch when he was in California and Tupac would always stop by Biggie’s neighborhood when he was in New York.

In essence, they were like any other pair of friends.

And the potential greatness of their combined talents was also evident. At the 1993 Budweiser Superfest at New York City’s Madison Square Garden, they freestyled together. Biggie often turned to Tupac for advice in the business — and even asked him to manage his career. But Tupac didn’t mix business with friendship: “Nah, stay with Puff. He will make you a star.”

Biggie Smalls and Sean "Puff Daddy" Combs at the Shrine Auditorium in Los Angeles, California

Biggie Smalls and Sean "Puff Daddy" Combs at the 11th annual Soul Train Music Awards in Los Angeles, California on March 7, 1997. Biggie died two days later.

Tupac believed Biggie had a hand in his 1994 gun down

While there were some smaller kerfuffles between Tupac and Biggie, the first big fallout happened when they were scheduled to work on a project together for another rapper, Little Shawn.

Tupac arrived at Times Square’s Quad Recording Studios on November 30, 1994, and was getting ready to head upstairs to where Biggie and Combs were. But instead, Tupac was gunned down in the lobby and shot five times, according to the New York Times.

He survived the attack but believed Biggie might have something to do with it, even though they did make it upstairs to see them right after the incident. “Tupac said the crew looked surprised and guilty, but Puffy claimed they showed him ‘nothing but love and concern,’” according to the Vice excerpt.

READ MORE: Inside Notorious B.I.G.'s Final Days and Drive-By Murder in Los Angeles

When Tupac joined Death Row Records, the East Coast-West Coast rivalry was cemented

While Tupac was incarcerated for another incident, he came to believe Biggie knew about the attack ahead of time. The west coast rapper reached out to Suge Knight, who offered him a place on his Death Row Records roster. Tupac accepted, cementing the rivalry between Knight's label and Combs’ Bad Boy Records. “Any artist out there that wanna be an artist, stay a star, and won’t have to worry about the executive producer trying to be all in the videos, all on the records, dancing—come to Death Row!” Knight proclaimed at that 1995 Source awards show.

There was never proof that Biggie or Combs knew about the incident. But a couple of months later, Biggie’s B-side single was a track called “Who Shot Ya?” which led to Tupac’s response with the song, “Hit ‘Em Up.” In it, Tupac claimed he slept with Biggie’s wife, Faith Evans. According to Vibe, Evans denied the claim, saying, “That ain’t how I do business.”

The punches continued to be thrown throughout their short lives, each side blaming the other for the deaths (while other theorists believe they may still be alive).

But after Tupac’s death, Biggie wanted to put an end to the coast-to-coast fighting. “We two individual people, we waged a coastal beef...one man against one man made a whole West Coast hate a whole East Coast. And vice versa. And that really bugged me out,” he said in an interview. “I've got to be the one to try to flip it... because Pac can't be the one to try to squash it because he's gone.”