Chinese music covers a highly diverse range of music from traditional music to modern music. Chinese music dates back before the pre-imperial times. Traditional Chinese musical instruments were traditionally grouped into eight categories known as ''bayin'' (八音). Traditional Chinese opera is a form of musical theatre in China originating thousands of years and has regional style forms such as Beijing opera and Cantonese opera. Chinese pop (C-Pop) includes mandopop and cantopop. Chinese rap, Chinese hip hop and Hong Kong hip hop have become popular in contemporary times.