Dunhuang manuscripts
Until the mid-20th century, the oldest complete rime dictionaries known were the "Guangyun" and "Jiyun", though extant copies of the latter were marred by numerous transcription errors. Thus all studies of the "Qieyun" tradition were actually based on the "Guangyun". Fragments of earlier revisions of the "Qieyun" were found early in the century among the Dunhuang manuscripts, in Turfan and in Beijing.