What is Yuefu folk song?

Yuefu is a music institution established by the government during the period of Emperor Wu of the Han Dynasty. Its main functions include collecting folk music, composing lyrics, adapting music scores, and arranging music. Later generations called the poems collected in Yuefu "Yuefu Poetry", "Han Yuefu" or Yuefu folk songs. Compared with The Book of Songs and Songs of the South, the greatest feature of Han Yuefu is narrative. Both The Book of Songs and The Songs of the South are mainly lyrical, while Yuefu in the Han Dynasty is "based on things" and often uses the third person to describe a thing. Another feature of Yuefu folk songs is that they adopt different poetic forms from The Book of Songs and Songs of the South: miscellaneous words and five words. The miscellaneous words in Han Yuefu are completely free, and there are more and more five-character poems, which gradually tend to be neat. The ideological content and artistic form of Yuefu folk songs have great influence on later poetry creation. Jian 'an literati used old Yuefu poems to reflect social disorder. In the Tang Dynasty, both Li Bai and Du Fu wrote Yuefu poems, which made it easy for them to create a "new Yuefu".