GIS-based Spatial-temporal Analysis of Castle-based Military Settlements in the Ming Great Wall Defense System of Yulin Zhen, Shaanxi Province, China

As a critical component of the Ming Great Wall Military Defense System (M-GWMDS) of Yulin Zhen in Shaanxi Province, China, castle-based military settlements have a horizontal distribution composed of three military routes and a vertical distribution consisting of two defense lines. These settlements played a key role in supervising the defense area and deploying troops. Exploring the spatial and temporal distribution of castle-based military settlements is a key link to revealing the in-depth distribution pattern of the M-GWMDS, but most studies have focused on their macroscopic distribution from a qualitative perspective. In this study, castle-based military settlements were selected as the research objects and were combined with architectural, archaeological, geographic, and military information. Their spatial and temporal analysis, including kernel density, slope/aspect conditions, and river systems, was explored based on GIS tools. By illustrating the military distribution nephogram and introducing the reachable spatial-temporal domains and viewshed, the deployment of military troops in this system was interpreted in depth. Taking both geographical and military factors into consideration, the XTENT model was comprehensively established to quantify the sphere of influence of castle-based military settlements, and the ranking and weights of factors influencing their distribution were eventually determined to illustrate the site catchment of these settlements, revealing the layout characteristics of the Ming Great Wall in the spatial and temporal dimensions to further reflect the military wisdom of the ancients. This research presents a new approach to thoroughly reveal the layout characteristics of the Ming Great Wall from a quantitative perspective, which will be beneficial to their subsequent protection and management.