Cao Pi was one of the leading figures of Jian'an Literature. About 40 or so his poems survived to this day. Most of the poems are in the Han-Dynasty folksong style. His most remarkable contribution to literature was five and seven-character poems. The poem entitled Yangexing was the earliest complete seven-character poem in the history of Chinese poetry. In addition, Cao Pi's prose was smooth, graceful and full of life and lyricism. His best works include A Letter to Wu Zhi and Another Letter to Wu Zhi among others. His literature critical work On Literature held an important position in the history of Chinese literature criticism.