How many years has Chinese herbal medicine culture existed in China?

More than two thousand years. Because Shennong's Classic of Materia Medica is the first book on Chinese medicine culture in China, this book was written by Han people and recorded the Chinese medicine culture in Qin and Han dynasties. Qin and Han dynasties were about two thousand years ago.

Traditional Chinese medicine is commonly known as "materia medica" in China ancient books. The earliest monograph on traditional Chinese medicine in China is Shennong's Herbal Classic in Han Dynasty, and the Newly Revised Materia Medica promulgated by the government in Tang Dynasty is the earliest pharmacopoeia in the world. Li Shizhen's Compendium of Materia Medica in Ming Dynasty summarized the experience of drug use before16th century, and made great contributions to the development of pharmacology in later generations.