Three Fanzhen of Hebei
The Three Fanzhen of Hebei (河朔三镇) were three regions of what is now Hebei, China governed by powerful jiedushi during the Tang dynasty (618-907 CE). After the devastating Anshi Rebellion, this area became virtually independent of the central government, as these regions were controlled by ex-rebel generals who had substantial territory and forces. The independence of these fanzhen threatened the central government of the Tang dynasty.
The Tang empire in the post-rebellion era shrank considerably in size. The dominant presence the Tang had maintained in Xinjiang from Emperor Taizong of Tang's reign had been threatened as early as 751 when at the battle of Talas the Arabs defeated the Tang forces under the ethnically Korean General Gao Xianzhi (高仙芝), dislodging them from Transoxiana. Not long after, the Tubo expanded into the areas in Xinjiang, Qinghai, and Gansu that had been abandoned since the Anshi Rebellon, while the Uyghurs built an empire that extended west from Mongolia into northern Xinjiang. Internally, as a number of defense commands evolved into autonomous kingdoms, their military commissioners became warlords, with only nominal ties to the Tang court. Particularly recalcitrant were Chéngdé 成德 (in Hebei), Lúlóng 盧龍 (in Hebei) and Wèibó 魏博 (in north Henan, southeast Hebei, and west Shandong) in the Hebei area. The central court was all but helpless in the northeast. In the south however, it 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 this region was briefly subdued by the central government, 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 chancellor Niu Sengru:
"Ever since the Anshi Rebellion, the three Fanzhen has not been part of the country. Although Liu Chong briefly gave the area to the central government, in the end it became independent and 80 million strings of cash were wasted. These regions are fought over frequently; one day Zhicheng has it, the next day Daiyi. As long as the jiedushi can fend off the northern barbarians, we will not care about its allegiance."