The "Treatise on Cold Damage Disorders and Miscellaneous Illnesses" was collated by Zhang Zhongjing, also sometime at the end of the Han dynasty, between 196 and 220 CE. Focusing on drug prescriptions, it was the first medical work to combine Yinyang and the Five Phases with drug therapy. This formulary was also the earliest Chinese medical text to group symptoms into clinically useful "patterns" ("zheng" ) that could serve as targets for therapy. Having gone through numerous changes over time, it now circulates as two distinct books: the "Treatise on Cold Damage Disorders" and the "Essential Prescriptions of the Golden Casket", which were edited separately in the eleventh century, under the Song dynasty.