In order to strengthen centralization, Emperor Wu of the Han Dynasty established the secretariat system in the fifth year of Yuanfeng (before 106), and divided the whole country into 13 monitoring areas. The prison area is called the state, and the state has a secretariat. In addition to 13 state, there are Sanfu (Jingzhao, Youfufeng and Zuofengyi), Sanhe (Hanoi, Henan and Hedong) and Hongnong seven counties, which are at the same level as the state and directly under the central government, and are responsible for the areas near the capital. Together with 13 state, it is called 14 state.

The states in the Western Han Dynasty were only monitoring areas, not real administrative areas. The real administrative region is only at the county and county levels, and the county satrap directly contacts the central government without going through the state level.

At the end of the Eastern Han Dynasty, the state was changed from a prison area to an administrative area, becoming a first-level administrative division at or above the county level, forming a three-level system of state, county and county. The whole country is still 13 state, which is equivalent to the current "provincial" administrative unit. This system lasted for about 400 years.