Stone City
In 727 and 728 the Tibetan Empire attacked Qiuci. In 737 the Tibetan Empire conquered Lesser Bolü. In 741 the Tibetan Empire sacked the Stone City. In 745 the Tang general Huangfu Weiming attacked the Stone City but suffered a major defeat. According to Huangfu, the Stone City was one of the most heavily defended bastions of the Tibetan Empire: