Types and historical roles of secret gates: a new understanding of the Ming Great Wall based on a digital heritage survey

Abstract

ABSTRACT The database of images of the Ming Great Wall, along with on-site investigation and verification, has allowed more than 120 secret gate sites to be located and classified for the first time. Based on typological analyses of the relationship between each type of secret gate’s form and function, we created a classification system of the Ming Great Wall’s secret gates. By combining traditional historical textual research, site surveys, and GIS micro-terrain analysis, we found that secret gates, as a key element, integrate other facility types into a coordinated regional defense system, revealing several active and flexible defense modes and more sophisticated planning intentions than were initially recognized. Finally, based on historical textual research, we found that secret gates played a broad and positive role in political interaction and socio-economic exchanges between the Ming Dynasty and Mongolian tribes, offering a new perspective on the historical function and the “open” or “closed” nature of the Ming Great Wall. Moreover, the methods introduced are likely to be applicable to the examination of other types of cultural route heritage.