Blues originated in the 17th century among African slaves in America and has traditionally focused on themes of sadness and depression. Rap music developed from hip hop culture in New York in the 1970s as a form of rhyming lyrics spoken over beats. Country music originated in the southern United States as a blend of popular musical styles. Jazz began in early 1920s New Orleans from a fusion of Western and African musical traditions. Classical music refers to European art, church, and concert music spanning from 1000 AD to the present day. Rock and roll evolved from rhythm and blues in the 1950s and was popularized by disc jockey Alan Freed.