Located in the key geographical position and shouldering the special mission of checking a possible intrusion from Heshuo, guarding the broad areas of Jianghuai, defending the Great Canal and protecting the two capitals, the military governors in Central Plains in the Tang Dynasty kept an enormous numbers of troops. After the midTang Dynasty, military expenditure had to be supported by the local governments themselves. As a result, the more troops a military governor kept meant the more military expenditure he had to provide, hence an extremely heavy burden for local governments to provide military expenditure. Under such circumstances, it proved an effective means to remit the difficulty of supporting troops to try to obtain rewarded military expenditure from the central government. Therefore, those military governors frequently sent their troops for expedition as their performance to be politically loyal to the court and out of their direct motivation to obtain the central government’s support of military expenditure.

the Tang Dynasty; the military governors in Central Plains; military expenditure to the size of troops