Ska (/ˈskɑː/, Jamaican [skjæ]) is a music genre that originated in Jamaica in the late 1950s and was the precursor to rocksteady and reggae. Ska combined elements of Caribbean mento and calypso with American jazz and rhythm and blues. It is characterized by a walking bass line accented with rhythms on the off-beat. Ska developed in Jamaica in the 1960s when Prince Buster, Clement "Coxsone" Dodd, and Duke Reid formed sound systems to play American rhythm & blues and then began recording their own songs. Some suggest ska dates to earlier times, however. In the early 1960s, ska was the dominant music genre of Jamaica and was popular with British mods. Later it became popular with many skinheads.