In 718, with a group of Eastern Tujue people having submitted to Tang in the aftermaths of the death of the Eastern Tujue khan Ashina Mochuo, Zhang Jiazhen suggested that a military base be established to help curb in the Eastern Tujue people. Pursuant to his suggestion, Tianbing Base (天兵軍) was established at Bing Prefecture, and Zhang was put in command of the base. In 718, Zhang was in Chang'an when there were accusations made that he was overly luxurious and corrupt while at Bing Prefecture. The chief imperial censor Wang Jùn thus indicted him, but after investigation, Zhang Jiazhen was cleared. Emperor Xuanzong considered executing the accuser as punishment for the false accusation, but Zhang pointed out that such an execution would have a chilling effect on the report of wrongdoing. Emperor Xuanzong thus only exiled the accuser, and he came to believe that Zhang was faithful and capable of greater duties, informing Zhang that one day he would likely be chancellor. Zhang responded: