Premise: West Coast hip hop is a hip hop music subgenre that encompasses any artists or music that originate in the West Coast region of the United States. The gangsta rap subgenre of West Coast hip hop began to dominate from a radio play and sales standpoint during the early 1990s with the birth of G-funk and the emergence of Suge Knight and Dr. Dre's Death Row Records.
Hypothesis: It started dominating in the century before the current century