Fanzhen in the context of "Military district"

The jiedushi or jiedu was a regional military governor in imperial China. The title was established in the Tang dynasty and abolished in the Yuan dynasty. The post of jiedushi has been translated as "military commissioner" or "governor", "legate", and "regional commander". Originally introduced in AD 711 to counter external threats, the jiedushi were posts authorized with the supervision of a defense command often encompassing several prefectures, the ability to maintain their own armies, collect taxes and promote and appoint subordinates.

Powerful jiedushi warlords eventually became fanzhen rulers, able to override the power of the central government of Tang. An early example of this was An Lushan, who was appointed jiedushi of three regions, which he used to start the An Lushan Rebellion that abruptly ended the golden age of the Tang dynasty. Even after the difficult suppression of that rebellion, some jiedushi such as the Three Fanzhen of Hebei were allowed to retain their powers due to the weakened state of the court. The jiedushi were one of the primary factors which contributed to the political division of the Five Dynasties and Ten Kingdoms period, a period marked by continuous infighting among rival kingdoms, dynasties, and regional regimes established by the jiedushi.

The Three Fanzhen of Hebei (Chinese: 河朔三镇; pinyin: Hé shuò sān zhèn) were three regions in what is now Hebei, China governed by powerful jiedushi in the post-An Lushan Rebellion (755-763) Tang dynasty (618–907). After the rebellion, the three regions of Chéngdé (成德), Lúlóng (盧龍) and Wèibó (魏博) were controlled by ex-rebel generals who held substantial territory and forces. Although nominally under the authority of the Tang dynasty, they were functionally independent fanzhen that continued to the end of the Tang dynasty. In the south, however, the court took a much more aggressive stand against such defense commands as Zīqīng (淄青) (mainly in Shandong), Biànsòng (汴宋) (in east Henan), and Huáixī (淮西) (in south Henan), which posed a more immediate and palpable threat to the transportation of strategic grains through the Grand Canal, on which the court depended.

During Emperor Xianzong's reign the northeast region was briefly subdued, but after his death it became independent again. By the reign of Emperor Wenzong, the central government had lost all control over this region. The situation was summed up thus by Tang dynasty's chancellor Niu Sengru: