How did special commissioners inspect local governments under Taizong?

Under the reign of the Taizong emperor, the central government maintained standardized and efficient local administration by dividing the country into 10 provinces known as "circuits."1

These circuits were not permanent administrative units but were instead established to facilitate occasional regional inspections of local governments. These inspection tours were conducted by special commissioners—often members of the censorate—who were dispatched from the capital to oversee the activities of local officials. This system provided the central government with an additional mechanism to ensure that prefectures and counties adhered to centrally codified laws and procedures regarding critical matters such as tax collection, land allocation, and the maintenance of law and order.12