The earliest Chinese manual of materia medica, the Shennong Bencao Jing (Shennong Emperors Classic of Materia Medica), was compiled in the 1st century AD during the Han dynasty, attributed to the mythical Shennong. It lists some 365 medicines, of which 252 are herbs. Earlier literature included lists of prescriptions for specific ailments, exemplified by the Recipes for Fifty-Two Ailments found in the Mawangdui tomb, which was sealed in 168 BC. Succeeding generations augmented the Shennong Bencao Jing, as in the Yaoxing Lun (Treatise on the Nature of Medicinal Herbs'), a 7th-century Tang dynasty treatise on herbal medicine.