Middle Chinese , formerly known as Ancient Chinese, is the historical variety of Chinese that is phonologically recorded in the Qieyun, a rime dictionary first published in 601 and followed by several revised and expanded editions. The fanqie method used to indicate pronunciation in these dictionaries, though an improvement on earlier methods, proved awkward in practice. The mid 12th-century Yunjing and other rime tables incorporate a more sophisticated and convenient analysis of the Qieyun phonology. The rime tables attest to a number of sound changes that had occurred over the centuries following the publication of the Qieyun. Linguists sometimes refer to the system of the Qieyun as Early Middle Chinese and the variant revealed by the rime tables as Late Middle Chinese.