During its five-hundred-year history the Koryŏ's local administration (kunhyŏn) system experienced a gradual evolution. By 1018 through a series of reforms its major contours emerged. Local administrations were subdivided into capitals, greater prefectures, districts, prefectures, counties, and garrisons. However, within the local administration the most important division was between the control counties that received officials dispatched from the central government and the subordinate counties that did not. From the middle of Koryŏ the role of the circuit gradually became more important, as it functioned as a superior administrative unit and became fully institutionalized by the end of Koryŏ. Lower level administrative units within the local administration were the ch'on, li, and tong, but special administrative units were divided among the stations, townships, pugok, so, chang, ch'ŏ, ch'ang, chin, and to. As the kingdom met new challenges the number of control counties expanded so that by the end of Koryŏ there were over 500 control counties and the number of subordinate counties decreased. The Chosŏn local administration system consolidated its regional governance into 330 counties together with a circuit administration of 8 circuits.