"Pingshui Yun" (Pingshui Yun Department) is named after its publisher, Liu Yuan, a native of Pingshui in the late Song Dynasty. Pingshui Yun divided Chinese characters into 107 rhymes based on the rhyme usage of the Tang Dynasty (his book is now lost). Each rhyme part contains a number of words. Rhyme is used to compose poems. The words in the rhyme must come from the same rhyme part and cannot be used incorrectly. Lu Fayan's "Qie Yun" in the Sui Dynasty was divided into 206 rhymes, which was too detailed. The Tang Dynasty stipulated that similar rhymes could be used together, so the actual simplified version of the Tang Dynasty's "Qie Yun" was 193 rhymes. Liu Yuan, who was originally from Pingshui, Shanxi Province in the Southern Song Dynasty, merged the same rhymes into 107 rhymes when he wrote "The Rhyme of Renzi Xinkan of the Ministry of Rites". At the same time, Wang Wenyu, an official in Pingshui, Shanxi Province and a Jin man, wrote "Pingshui Xinkan Yunlue" with 106 rhymes. In the Qing Dynasty "Pei Wen Yun Fu" compiled during the Kangxi period combined "Ping Shui Yun" into 106 rhymes, which became the widely circulated Ping Shui Yun.