China Historical GIS, Harvard University and Fudan University CC BY-NC 4.0 https://maps.cga.harvard.edu/tgaz/placename/hvd_111597 陝虢都防禦觀察使 陕虢都防御观察使 Shanguo Dufangyuguanchashi 防镇 防鎮 fang zhen defense command 836 4 881 4 POINT point N 34.65606 E 111.36268 唐 Tang CHGIS