There are few coincidences in hip-hop history quite as eerie as Sept. 13.

On Sept. 13, 1994, The Notorious B.I.G. released his debut album, Ready to Die. Exactly two years later, Tupac Shakur died at 25 after being shot in Las Vegas six days earlier.

The two years between those moments contain nearly the entire story of how two friends became the faces of hip-hop’s most infamous rivalry.

When Ready to Die arrived, Biggie was still emerging while Tupac was already an established rapper and actor. The two knew each other, spent time together and had not yet become permanently associated with opposing sides of a coastal feud.

That changed rapidly. On Nov. 30, 1994, Tupac was robbed and shot at Quad Recording Studios in Manhattan. Biggie and Sean “Puffy” Combs were in the building, and Tupac later publicly voiced suspicions about people surrounding Bad Boy. Biggie denied involvement, and there has never been evidence establishing that he orchestrated the shooting.

By 1996, Tupac was signed to Death Row Records, and the personal fallout had become tangled with the larger Bad Boy-Death Row and East Coast-West Coast conflicts. Tupac made his feelings unmistakable on “Hit ’Em Up,” directly targeting Biggie and Bad Boy.

On Sept. 7, 1996, Tupac was shot after attending the Mike Tyson-Bruce Seldon fight in Las Vegas. He died six days later.

Six months after Tupac’s death, Biggie was shot and killed in Los Angeles on March 9, 1997, at just 24. His second album, Life After Death, arrived 16 days later.

Biggie and Tupac’s relationship has since been flattened into a simple story of enemies and coasts, but Sept. 13 preserves a stranger, more complicated connection: the date Biggie’s career changed forever also became the date Tupac’s life ended.