The system was a model of Chinese administrative units established for foreign rulers or chiefs that were either militarily subdued or self-subdued and naturalized. They received their duty from the central authority while keeping their original status, and passed on their duty to heirs. They were to provide annual tribute, following the foreign policy of the central authority and under its supervision. The system was first introduced by commander
Li Daliang between August 23 and September 25, 630. It mainly consisted of three levels: the command area (),
prefecture () and
county (). Known collectively as Jimifuzhou or the
loose-control administrative units, they were not commonly confused with Zhengzhou () or the
regular administrative units. In additions, there were also two loose-control protectorates (
duhufu 都護府) established in the former
Western Turkic Khaganate around the
Tarbagatai Mountains and
Lake Balkhash in 658, the only loose-control protectorates ever established. In some cases, a moderate number of loose-control counties were also established under the jurisdiction of a regular prefecture at the border of Tang proper. They were established in the areas of today's northern
Hebei, northern
Shaanxi,
Gansu,
Ningxia,
Inner Mongolia, Outer Mongolia, Siberia, Sogdiana and Afghanistan to the north and west,
Hunan and
Guangxi to the south, western
Sichuan,
Guizhou and
Yunnan to the southwest, where they co-existed with the regular prefecture, and also parts of Inner and Central Asia during the early Tang empire. Until 755, there were approximately 1,000 or around 856 loose-control prefectures established within the former khaganate and state, about 2.6 times the regular prefecture. ==See also==