The music of the Philippines is diverse, the indigenous people being spread across hundreds of islands and among 140 ethnic groups. It has in addition been influenced by Indonesian gamelan and other Asian styles, and by more than four centuries of colonial rule by Spain and the United States. Christian religious music was introduced early on. The Spanish guitar and Zarzuela (a form of operetta) also became popular, and more recently American blues, folk, rock’n’roll, pop and jazz have all made an impact.