You Framed Me, Now You Need Me?

Li Jin, third son of the emperor of Dayuan, held the northern border for three years. During that period the emperor, the empress and the crown prince, his elder brother, brought a charge against him. He was taken to Dragon Cliff and made to go over the edge. He survived the fall. He stayed in the north and did not report back. He gathered people there and set himself up as their king. The Beidi came south and put the capital under siege. The court that had condemned him sent word asking him to come. He came back with his face covered, under the name King of the North. The Beidi khan was in the field outside the capital by then.