Zhang is the oldest fairy in ancient Han myths and legends, and has a wide influence among Han people. He is a real historical figure. "Zhang () was originally a Taoist priest of Guangzong and Xingzhou, whose real name is Sir. His thoughts are mainly based on Tao Te Ching, Miao Zhen Ching, Huang Ting Ching and Shen. He is a famous alchemist, health care practitioner and philosopher in the Tang Dynasty. "