 After Emperor Mingzong died in 933 , the Later Tang began to crumble from its own succession crisis . Mingzong 's son and successor Li Conghou ruled for only five months before he was killed in 934 in a coup led by his adoptive brother Li Congke ( Emperor Mo of Later Tang ) . Prince Bei , who was still an honored guest at the Tang court at the time , wrote to his brother Emperor Taizong ( Yelü Deguang ) , advising him to invade the Tang . Instead , Taizong lent military support to a rebellion led by Shi Jingtang , a Tang governor and son @-@ in @-@ law of the former Emperor Mingzong . With Khitan help , in 936 Shi Jingtang succeeded in replacing the Later Tang with his own Later Jin . After some negotiation with the more powerful Khitans , he ceded sixteen border prefectures stretching from modern @-@ day Datong ( Shanxi province ) to the coast of the Bohai Sea east of what is now Beijing , to the Liao . Since the Sixteen Prefectures contained numerous strategic passes and fortifications , the Khitans now had unrestricted access to the plains of northern China . Shi Jingtang also agreed to treat Emperor Taizong of Liao as his own father , a move that symbolically elevated Taizong and the Liao to a superior position . 
