Tang military commanders have begun to accumulate independent political strength in the latter years of Xuoyang’s reign.

When the emperor's concubine, Yang Guifei, becomes a power at the imperial court, one such general, An Lushan, rebels against the empire rather than lose influence.

A semi-barbarian of Persian and Turkish descent, raised in Mongolia, An Lushan had moved to China as a young man and joined the army, rising rapidly through the ranks to become a court favorite of the emperor and military governor of three northern Chinese provinces.

At the death of the emperor’s powerful chief minister, An Lushan had applied for the vacant post but was denied it; Yang Guifei’s appointment had been the final straw.

An launches his rebellion on December 16, 755, claiming that he has received a secret edict from Emperor Xuanzong to advance on Chang'an to remove Yang.

The imperial officials are all apprehensive, because An has the strongest troops of the realm at the time, except for Yang, who believes that An can be suppressed easily.

Emperor Xuanzong, meanwhile, commissions the general Feng Changqing as the military governor of Fanyang and Pinglu, intending to have him replace An after An's rebellion is defeated.

The Emperor also sends Feng to the eastern capital, Luoyang, to build up the defense there; another general, Gao Xianzhi, is ordered to command a secondary defense at Shan Prefecture (roughly modern Sanmenxia, Henan).

He also executes An Qingzong and An's first wife Lady Kang, and forces An Qingzong's wife Lady Rongyi to commit suicide.