Donguibogam (Principles and practice of Eastern medicine) is an encyclopedia of medical knowledge and treatment techniques compiled and edited by Heo Jun, with the collective support of other medical experts in Korea. Heo Jun, a court physician, received a royal command to write a medical book to assist people suffering from famine brought about by war and drought during the rule of King Seonjo (1552–1608, reigned, 1567–1608). Heo Jun himself picked the proper medicinal herbs, which were native to the Korean Peninsula. He conducted human clinical trials to test the efficacy of the medicines, and he wrote the names of the herbs in Korean so that the common people could learn them. For ease of use, the contents of the encyclopedia were divided into five categories: Naegyeong (Internals), Oehyeong (Externals), Japbyeong (Various diseases), Tangaek (Herbal juices), and Chimgu (Acupuncture). Donguibogam was disseminated as far as Japan and China and informed the evolution of medicine in East Asia and beyond. In terms of health care systems, it promoted preventive medicine and public health care by the state, which were ideas virtually unknown until the 19th century. Donguibogam was inscribed on the UNESCO Memory of the World Register in 2009.