The two-tier local government administration of prefectures and counties took shape between the late Spring and Autumn Period and the early Qin Dynasty. Back in the Spring and Autumn and Warring States periods, some kingdoms established county or prefectural administration in newly annexed areas, but the two were separate jurisdictions. When the First Emperor of Qin(259-210 BC) unified China, he abolished the enfeoffment system that was based on consanguinity and established a vertical government system of prefectures and counties under which the central government exercised jurisdiction over prefectures, and prefectures exercised jurisdiction over counties. Heads of prefectures and counties were appointed and dismissed by the central government. The Chinese word for prefect was shou (守，changed to taishou 太守 by Emperor Jing of the Han Dynasty); and a county head was called ling（令） or zhang（长）. In the early Han Dynasty, both enfeoffment and the prefecture-county system were practiced. Gradually the latter prevailed. The prefecture-county system strengthened autocratic-imperial rule and was a key component of the centralized power system.

Later scholars believed the abolition of enfeoffment and the establishment of prefectures and counties were carried out by the First Emperor of Qin, but I don't think so. (Gu Yanwu: Records of Daily Study)

Before the Shang and Zhou dynasties, there were kingdoms of five ranks; they all had their own armies, and the strong bullied the weak and annexed their land. The First Emperor of Qin abolished the feudal kingdom system and set up prefectures. All later dynasties followed this model, adopting the government systems of prefectures and counties.

(Du You: An Encyclopedic History of Institutions)