Shi Jingtang
In 929, the Khongirad rebelled. In 929, Taizong sent his younger brother, Yelü Lihu, to attack the Later Tang at Datong. In 933, Taizong led a campaign against some Tangut tribes. The most important expansion of Khitan territory during this period, however, came from political instability in the south. In 933, the Later Tang emperor died. His son, Li Conghou, lasted only five months before his adoptive brother, Li Congke, killed him. Li Congke ordered a powerful governor, Shi Jingtang, to be transferred for closer supervision by the court, leading to his rebellion. Hard pressed by Li Congke, Shi Jingtang sought aid from the Khitans. Taizong led a 50,000 strong cavalry force to his aid and defeated the Later Tang army near Taiyuan. On 28 November 936, Shi Jingtang was invested as emperor of Later Jin by the Khitans. In 938, the puppet emperor of Later Jin transferred the Sixteen Prefectures over to the Khitans, granting them access to the strategic fortifications of northern China and the Central Plains. A new "Southern Capital" (Nanjing) was constructed at modern Beijing. Shi Jingtang behaved as a vassal and even allowed Khitan envoys to cross his territory to contact Southern Tang, his geopolitical rival.