Zhongyuan Yinyun

Zhongyuan Yinyun (simplified Chinese: 中原音韵; traditional Chinese: 中原音韻; pinyin: Zhōngyuán Yīnyùn), literally meaning "The phonology of the Central Plains", is a rime book from the Yuan Dynasty compiled by Zhou Deqing (周德清) in 1324. An important work for the study of historical Chinese phonology, it testifies many phonological changes from Middle Chinese to Old Mandarin, such as the reduction and disappearance of final stop consonants and the reorganization of the tones. Though often termed a "rime dictionary", the work does not provide meanings for its entries.