[Why] Later Tang internal coups were frequent, and the military governor Shi Jingtang rose in rebellion but was heavily besieged by Later Tang forces. To survive and seize power, he resolved to lean on the vast cavalry military force of the northern Khitan empire. [What] Shi Jingtang did not spare himself from declaring himself the child emperor to the Khitan khan and decisively ceded the critical Sixteen Prefectures of Yan-Yun frontier garrisons. Relying on Khitan force he wiped out Later Tang and founded the puppet Later Jin regime. [Who] Shi Jingtang in Chinese historical record is despised as the archetypal child emperor who bent his back and sold his country's security. Liao Emperor Taizong Yelu Deguang was the wily and sharp northern hero who pocketed the northern Huaxia defense line with a smile. [How] The cession of the Sixteen Prefectures of Yan-Yun caused Central Plains agricultural civilization to lose nearly four centuries of strategic defense behind the Great Wall barrier. It directly exposed the Central Plains to nomadic-cavalry hooves, with limitless future calamity.
Why
The historic event of Cession of the Sixteen Prefectures represents a key developmental peak of the Huaxia dynastic system. The catastrophic cession that lost the northern natural barrier for nearly four centuries. By establishing this moral or administrative benchmark, it continues to shape the structural and philosophical fabric of ancient Chinese statecraft.