Zhang Zhihe's biographical information is very limited in publicly available sources: his nationality, dates of birth and death, and educational background are all unknown. What can be confirmed at present is only one surviving work, the Outer Chapters of Xuanzhenzi (Xuanzhenzi Waipian). The book is classified under Eastern philosophy and serves as the main entry point for understanding Zhang Zhihe's thought. Judging from its title and classification, the work carries Daoist and metaphysical overtones; using "Xuanzhenzi" as a sobriquet or pseudonym, its main text consists largely of discursive prose on self-cultivation, nature, and the way of the cosmos, in a concise language that at times reaches speculative heights. Owing to the scarcity of historical records, we cannot outline the author's full life or intellectual lineage, nor judge his specific position in the scholarship of his time. Nevertheless, the fact that the Outer Chapters of Xuanzhenzi has survived suggests that it was read, copied, and valued within a certain circle, and it offers reference value for studying the recluse and speculative traditions in ancient Eastern philosophy. To read Zhang Zhihe, one should rely on his book and treat later conjectures with caution.
