However, Xianyu Zhongtong detained the Nanzhao envoys and turned down the appeal. Confronted with Tang armies, Nanzhao immediately turned its allegiance to the Tibetan Empire.[26] The Tubo and Nanzhao agreed to be "fraternal states"; Geluofeng was given the titles zanpuzhong ("younger brother"). The Nanzhao-Tubo alliance ensured a disastrous defeat for Xianyu's expedition, with the Tang general's army of 80,000 men being reduced to a quarter of its original size.[27]