Shengqiang
Shengqiang is a concept in Chinese opera which helps to categorize its hundreds of regional genres by the music played during arias. Classifying by the music, as opposed to the regional dialect, also helps to understand a genre's evolutionary history. For example, Peking opera and Cantonese opera have little in common as far as language or place of origin, but they belong to the same shengqiang system. Today, the four major shengqiang are Bangziqiang, Pihuangqiang, Kunqiang and Gaoqiang. Not all Chinese opera genres fall into one of these four shengqiang systems, and many genres can be classified into more than one system. Other shengqiang in history include Yuyaoqiang and Haiyanqiang.