Pingshui Yun possibly originated as an abridged version of the
rhyme dictionary Guangyun, whose 206-rhyme system was criticized for being overly restrictive. The system was traditionally attributed to
Song dynasty scholar Liu Yuan (劉淵), whose 1252 work
Renzi Xinkan Libu Yunlüe (壬子新刊禮部韻略) divided common
Chinese characters in poetry into 107 rhyme categories. However, in 1223,
Xinkan Yunlüe (新刊韻略) was already published by Wang Wenyu (王文鬱) of the Jin dynasty. The latter's contents were almost identical to
Renzi Xinkan Libu Yunlüe, with the only difference being that Liu's book splits the rhyme category 迥 into two. A book unearthed from the
Mogao Caves named
Paizi Yun (排字韻) implies that the system was already widely circulated at the time. Both works have since been lost. In the
Yuan dynasty,
Yunfu Qunyu by Yin Shifu (陰時夫) first named the 106-category version as
Pingshui Yun. The origin of the name "Pingshui" is unclear. Traditionally, it is believed that "Pingshui" refers to Liu Yuan's hometown in modern
Linfen,
Shanxi. Alternatively, "Pingshui" may refer to a government post in charge of tax for fishing. In the Yuan, Ming and Qing dynasties, the
Pingshui Yun system was highly influential as the
Yunfu Qunyu version served as the official standard in the
imperial examinations. Although modern Chinese phonology has become significantly different from Middle Chinese, the system is still being used by some poets today. In addition to literary usage of this rime system, in early modern China when sending
telegraphs were expensive, the words in
Pingshui Yun were used to represent dates in order to reduce the number of characters as shown on the table on the right. ==Rhyme categories==