Wang Xingyu became the military governor of Jingnan in 887, which was, however, only six years after Huang Chao captured Chang'an in the Guangming era, which would place a timeframe to Zhang's becoming his assistant as perhaps in the early 890s. See Zizhi Tongjian, vol. 256.
Li Keyong's defeat of Wang Xingyu occurred in 895, dating this event. See Zizhi Tongjian, vol. 260.
Zhu Quanzhong forced Han Jian to give up Zhenguo and then transferred him to Zhongwu in 901, placing a timeframe on Zhang's service under Han. See Zizhi Tongjian, vol. 262.
