The Chinese controlling system in the Tang Dynasty was developed for the emperor to maintain the stable operation of his huge bureaucracy, with the positive function of eliminating corruption and degeneration. In the Tang Dynasty, Yu Shi Tai was a controlling department in the central government, but, owing to its limited human resources and multitudinous controlling and non-controlling tasks, the department was not able to cope with the huge body of officials. While performing its functions, Yu Shi Tai was often impeded by some external forces. As time went by, the performance of the department got increasingly poor. As the controlling officials of the central government could not take account of all officials in the empire, 'Si Lu Can Jun Shi' and 'Lu Shi Can Jun Shi,' the two controlling officials in a local government, were able to activate the controlling mechanism within their administrative areas, enabling the local government to deal with local affairs effectively, integrating the central and local controlling work and, accordingly, stabilizing the Tang Dynasty for nearly 300 years.