Gangsta rap or gangster rap is a style of hip hop characterized by themes and lyrics that generally emphasize the "gangsta" lifestyle. The genre evolved from hardcore rap 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 gangsta rap artists openly boast of their associations with various active street gangs as part of their artistic image, with the Crips and Bloods being the most commonly represented. Gangsta rap parallels other indigenous gang and crime-oriented forms of music, such as the narcocorrido genre of northern Mexico.