Gangsta rap or gangster rap is a subgenre of hip hop music with themes and lyrics based on the "thug" or "gangsta" lifestyle. The genre evolved from hardcore hip hop into a distinct form, pioneered in the mid-1980s by rappers such as Schoolly D and Ice-T, and was popularized in the later part of the 1980s by groups like N.W.A. After the national attention that Ice-T and N.W.A attracted in the late 1980s and early 1990s, gangsta rap became the most commercially lucrative subgenre of hip hop. Many (if not most) gangsta rap artists openly boast of their associations with various active street gangs as part of their artistic image, with the Bloods and Crips being the most commonly represented. Gangsta rap is closely related to other indigenous gang and crime-oriented forms of music, such as the narcocorrido genre of northern Mexico.