Rostrum Records president Benjy Grinberg first heard about Wiz Khalifa in 2004 when the rapper's contribution to a mixtape of various new Pittsburgh artists attracted his interest. When Grinberg finally met the 16-year-old artist, he immediately decided he wanted to work with him, later telling HitQuarters: "Even though he wasn't all the way developed you could just tell that he was a diamond in the rough, and that with some polishing, guidance and backing he could become something special." Khalifa signed to the label shortly after and began a seven-year period of artist development. Khalifa released his first mixtape, "Prince of the City: Welcome to Pistolvania", in 2005. The mixtape paved the way for his first full-length album entitled "Show and Prove" in 2006. Khalifa was declared an "artist to watch" that year in "Rolling Stone" magazine.