Ska jazz is a music genre derived by fusing the melodic content of jazz with the rhythmic and harmonic content of early Jamaican Music introduced by the "Fathers of Ska" in the late 1950s. The ska-jazz movement began during the 1990s in New York and London, where pioneering avant-garde jazz and reggae musicians pushed the boundaries of reggae music. They were combining traditions with modern tendencies, using the reggae beat along with high improvisation and jazz harmonies, primarily by horns and percussion.