Xue and Xue grew up poor, learned to write, practiced martial arts, gained strength, grew up to be farmers and married Liu.
In the late period of Zhenguan in Tang Dynasty, Emperor Taizong wanted to levy Korea himself. From the autumn of the eighteenth year of Zhenguan (644), we mobilized military supplies, recruited sergeants and actively prepared for war. Xue defected to the general and accepted him as his subordinate. Soon, when Emperor Taizong personally marched into North Korea, his troops went to Andi, and Lang was surrounded by local armed forces. Hearing this, Xue rode alone to rescue him, tied his head to the saddle, subdued the rest and rescued him to the camp. Since then, Xue has become famous in the three armed forces.