A$AP Mob is mourning the loss of its leader. A$AP Yams has died at the age of 26.

The visionary, born Steven Rodriguez, was credited as the founder and mastermind behind the Harlem group, and helped introduce the world to A$AP Rocky and A$AP Ferg.

When he was a teenager, Yams interned at Diplomat Records and managed local producers and sold mixtapes (via MTV News). At the age of 17, he founded A$AP Mob in 2007 with A$AP Bari and A$AP Illz.

In a profile in The New York Times, Rocky called Yams “the mastermind behind the scenes.”

“Yams is the hip-hop encyclopedia,” he said. “He’s no joke. That’s one person I can’t front on when it comes to music.”

His fellow A$AP Mob members including Rocky and Ferg mourned their brother’s passing, while his peers also expressed their sympathy.