It is characterized by "no definite sentence in writing, no definite word in sentence", relatively free syllables and meter, different syntactic lengths and rich changes. Songs after the Tang Dynasty generally adopt the genre of five-character ancient poems or seven-character ancient poems.
There is no strict requirement for format and rhythm, and it is not about straightness. The number of words is mainly five or seven words, which can be uneven and varied. Also known as ancient poetry and ancient style.
For example, Du Fu's Autumn Wind Broke the Hut, Cao Cao's Short Songs, Cao Pi's Yan Songs and so on.