The Golden Age and Its Rot

In the mid-eighth century, Tang China was the most populous, prosperous, and cultured empire on earth — the age of the immortal poets Li Bai and Du Fu, of a cosmopolitan capital at Chang'an that drew merchants and pilgrims from across Asia, of an empire that seemed the very definition of civilisation at its height. Over it presided the emperor Xuanzong, whose long reign had begun in vigour and reform.

But the golden age was rotting from within. In his old age Xuanzong wearied of rule, fell deeply in love with his beautiful young consort Yang Guifei, and let power drain to her grasping relatives — above all her cousin Yang Guozhong, who became a corrupt and hated chief minister. Meanwhile the empire had made a fatal structural mistake: to guard its vast frontiers, it had concentrated its best armies under powerful regional military governors, the jiedushi, far from the soft and undefended interior.

The greatest of these frontier lords was An Lushan, a huge, cunning general of Sogdian and Turkic blood who had charmed his way into the emperor's and Yang Guifei's affections and been given command of three military regions and nearly 200,000 of the empire's finest troops. Locked in a deadly feud with Yang Guozhong and grasping his own overwhelming strength, he decided to seize the throne itself. In December 755 he turned his frontier veterans south, against an empire that had known peace for so long it had almost forgotten how to fight.