On the Power Held by Military Governors During the Kaiyuan and Tianbao Periods in the Tang Dynasty

The power held by military governors increased during the Kaiyuan and Tingbao periods in the Tang dynasty,but things were different with different military governors.Military governors were effectively controled by the central government when they made use of their power.The central government also effectually prevented most of the military governors from becoming separatist warlords by transferring them frequently and limiting the areas under their jurisdiction.However,An Lushan,as a powerful military governor,was a special case originating from complicate causes.