Yan Gengwang (19 16- 1996), a famous historian, was born in Tongcheng, Anhui. 1940 graduated from the history department of Wuhan University. He used to be a researcher and professor at cheeloo university Sinology Institute, Academia Sinica Institute of History and Linguistics, Chinese University of Hong Kong Department of History, Sinology Institute and New Asia Institute. His main research fields are China's medieval political system and historical geography, and he has written History of China's Local Administrative System, Cheng Lang Table of Tang Servants and Merchants, Tang Shi Research Series, Traffic Map of Tang Dynasty, etc.