Fanzhen, also referred to as fangzhen, was a system of decentralized governance utilized in Medieval China. These were strategic military districts and commanderies located primarily along the empire's borderland areas. The system was characterized by high levels of autonomy for regional governors, who were known as jiedushi during the Tang dynasty.
The primary purpose of these districts was to serve as buffer regions intended to shield China's economically and politically vital heartlands from external threats. However, over time, the provincial military commissioners in charge of these areas became increasingly influential. During the late Tang period, many of these leaders evolved into ambitious warlords, rebels, and usurpers. Historians refer to this phenomenon of fanzhen domination as fanzhen geju.