Prohibition of Private Armies: The Tang emperors also prohibited aristocrats from maintaining private armies, which further reduced their military strength and made them less of a threat to the imperial throne.
Examination System: The Tang dynasty introduced a civil service examination system, which allowed talented individuals, regardless of their social status, to enter government service. This helped to break the monopoly of the aristocracy on government positions and opened up opportunities for social mobility.
Centralized Administration: The Tang emperors also strengthened the centralized administration of the empire, reducing the power of regional officials and aristocrats. They established a system of imperial inspectors to monitor local officials and ensure their loyalty.