In March, 670, Silla armies made it to the north of the Yalu river(鴨綠江). As T'ang armies led by General Hsueh Jen-kuei(薛仁貴) were completely wiped out in Kokonor in July, 670, the Silla came to rein most of the territory formerly occupied by the Paekche(百濟). At the time the Tibetan envoys arrived in Xi'an(長安) in a bid to cut a deal with the Tang's emperor Kao-tsung(唐 高宗) and the empress Wu(武后), Tang's selected troops of cavalry led by General Kao K'an(高侃) defeated Silla's central army troops(中央軍團) in a battle that took place on the Seokmoon(石門) in August 672. In December, Tang armies attacked Baeksu mountain (白水山) which Koguryo(高句麗) migrants were holding, mowing down Shilla's troops that came to back up its northern neighbor. In May, 673, Tang armies dealt a final blow to the Koguryo at the western part of the Im-jin river(臨津江). Its assault went on until the winter of 673. However, in 675 the situation turned about. As the Tibetan envoys initiated peace talks in Xi'an in January, Tang armies led by General Liu Jen-kuei(劉仁軌) moved southward to the southern area of the Imjin river the following month, devastating Chiljung(七重城) area and advancing to Meso(買省城). It was when the Malgal annies(靺鞨軍) took a seaway to take on the southern area, impairing Silla forces.