Shanghan Lun, also known as the "Treatise on Cold Damage," is a classical Chinese medical text attributed to the physician Zhang Zhongjing from the Han Dynasty. It focuses on diagnosing and treating diseases caused by cold pathogens, emphasizing the importance of understanding the progression of illness and the body's response to external factors. The text is structured around various patterns of illness and their corresponding herbal treatments. It serves as a foundational work in Traditional Chinese Medicine (TCM), influencing both clinical practice and herbal medicine. Its principles continue to be studied and applied in modern TCM practices.