The Book of Songs is the earliest poetry collection in China. Regarding the classification of poems in the Book of Songs, there is the theory of "Four Beginnings and Six Meanings". "Four Beginnings" refers to the top four poems of "Feng", "Daya", "Xiaoya" and "Song". The "six meanings" refer to "wind, elegance, praise, fu, bi, and xing". "Feng, Ya, and Song" are the classifications of the Book of Songs according to different music, and "Fu, Bi, and Xing" are the expression techniques of the Book of Songs.
"Wind" is also called "Guo Feng". There are 15 groups in one song. "Wind" is the general name of music. The 15 sets of national styles are not music from 15 countries, but music from more than a dozen regions. The national style includes 160 songs from Zhou Nan, Zhao Nan, Bei, Yong, Wei, Wang, Zheng, Hui, Qi, Wei, Tang, Qin, Bin, Chen and Cao. Guofeng was a popular local song at that time, with local flavor. In terms of content, most of them are folk songs. Most of the authors are folk singers, but there are also some nobles.