 It was said that Xue was a capable administrator and was, for a while, able to receive allegiance from the people of Goguryeo.In 670, Tibetan Empire launched a major attack on Tang's Anxi Protectorate and captured 18 prefectures.Emperor Gaozong commissioned Xue to command a counterattack, with Ashina Daozhen (), and Guo Daifeng (), the son of Tang's veteran general Guo Xiaoke (郭孝恪), as his deputies.