Question:  "ATLiens" is a song by a hip-hop group formed in which year ?
Sentence (from "Outkast"): Outkast (stylized as OutKast) is an American hip hop duo formed in 1991, in East Point, Atlanta, Georgia, composed of Atlanta-based rappers André "André 3000" Benjamin (formerly known as Dré) and Antwan "Big Boi" Patton.
Relevant evidence: Yes