[2] The term "Jimi" was first seen in the annotation of Shiji quoted by Sima Zhen from a book of the Eastern Han dynasty, which implied to a man directing a horse or ox by the use of rein.
[5] 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.
[10][11] In some cases, a moderate number[clarification needed] of loose-control counties were also established under the jurisdiction of a regular prefecture at the border of Tang proper.
[9] The loose-control administrative units, specifically the command area and prefecture, were established shortly after a region, state or tribe was subdued and formed as a political division within the extent of a separated regular protectorate.
[12] They were established in the area 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.