What is the earliest book that records tea as medicine?

The earliest book that recorded tea as medicine was Shennong Materia Medica. Shennong's Classic of Materia Medica, also known as "Classic of Materia Medica" or "Classic of Materia Medica", was written in the Han Dynasty and named Shennong. It is one of the four classic works of traditional Chinese medicine and the earliest known works of traditional Chinese medicine.

Legend originated from Shennong and was handed down from generation to generation. It was compiled into a book in the Eastern Han Dynasty. The book was not written in a moment, and the author was not alone. Many medical scientists in Qin and Han dynasties collected, summarized and sorted out the monographs on pharmaceutical experience at that time, which was the first book in China to systematically summarize traditional Chinese medicine. Most theories and compatibility laws of TCM and the principle of "seven emotions in harmony" have played a great role in the practice of medication for thousands of years and are the source of the development of TCM theory.