Zhāng Jī 張機 (zì Zhòngjǐng 仲景, fl. Jiàn’ān 建安 reign, ca. 196–220), traditionally given as a native of Nányáng 南陽 who held the post of Chángshā Tàishǒu 長沙太守 (Grand Protector of Chángshā), is the legendary author of the foundational Hàn-period clinical canon — the Shānghán zábìng lùn 傷寒雜病論, of which the surviving text-strata are the Shānghán lùn 傷寒論 (KR3e0007 and others) and the Jīnguì yàoluè 金匱要略 (KR3e0006). His historicity is unevenly attested: Hàn-period historical sources do not record him, and his attribution as Chángshā Tàishǒu is first found in the Tàipíng yùlǎn 太平御覽 (10th c.) on the authority of a Liáng-period biographical source. The earliest secure witness to him is Wáng Shūhé 王叔和’s compilation of the Shānghán lùn in the late third century — at most a generation after Zhāng’s putative date. From the Sòng校正醫書局 collation onward, Zhāng has been the foundational figure for clinical medicine (“醫聖” Yī shèng, the Medical Sage), as Huángdì is foundational for theoretical and Biǎn Què for diagnostic medicine. His preface to the Shānghán zábìng lùn — describing the loss of two-thirds of his own clan to epidemic disease in the Jiàn’ān decade — is the earliest extant first-person preface to any Chinese medical work and is the source of the conventional fl. dating.