黄帝内経
"Huangdi Neijing" (), and collecting many prescriptions elsewhere, finally writing the medical masterpiece "Shanghan Zabing Lun" (, lit. ""Treatise on Cold Pathogenic and Miscellaneous Diseases"). Shortly after its publication, the book was lost during the wars that ravaged China during the period of the Three Kingdoms. Because of Zhang's contribution to traditional Chinese medicine, he is often regarded as the sage of Chinese medicine.