Ska originated in Jamaica in the late 1950s, combining 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' (the 'upbeat'). Ska was the music of the optimistic, newly independent Jamaica. It typically features a prominent brass section (trumpets, saxophones, trombones) and a bright, fast tempo. The genre evolved through three distinct 'waves': the original Jamaican Ska, the '2 Tone' movement in late 1970s Britain (which added punk energy and addressed racial unity), and the 1990s Ska-Punk boom in the US. Ska's rhythmic structure—placing the emphasis on the 'and' of the beat—directly led to the development of Rocksteady and eventually the slower, more bass-heavy Reggae.