He was from Suiyang (睢陽, in modern Shangqiu, Henan), but little is stated about his family background in the traditional sources.
Late during Tang, he served as the military advisor to the prefect of Shan Prefecture (陝州, in modern Sanmenxia, Henan).
However, at one point, he took a leave to see his uncle Zhang Shensi (張慎思), who was then serving as the acting military governor of Ganhua Circuit (感化, headquartered in modern Xuzhou, Jiangsu).
He informed Zhang Shensi his opinion that northern China was about to fall into complete chaos and that he wanted to head to the region between the Yangtze and Huai Rivers (which was then under the rule of the major warlord Yang Xingmi the military governor of Huainan Circuit (淮南, headquartered in modern Yangzhou, Jiangsu)), so that the family line could be extended.
At that time, the general Zhang Xuan (張宣) was one of the commanders of the guards for the capital Guangling, and was, due to his accomplishments, arrogant and violent.
Zhang eventually was put in charge of overseeing all six ministries of the executive bureau of government (尚書省, Shangshu Sheng) and became respected by the people.