Heo Jun was a court physician of the Yangcheon Heo clan during the reign of King Seonjo

Seonjo of Joseon

King Seonjo ruled in Korea between 1567 and 1608. He was the fourteenth king of the Joseon Dynasty. He is known for encouraging Confucianism and renovating state affairs at the beginning of his reign, although political chaos and his incompetent leadership during the Japanese invasions of Korea...

 of the Joseon Dynasty

Joseon Dynasty

Joseon , was a Korean state founded by Taejo Yi Seong-gye that lasted for approximately five centuries. It was founded in the aftermath of the overthrow of the Goryeo at what is today the city of Kaesong. Early on, Korea was retitled and the capital was relocated to modern-day Seoul...

 in Korea

Korea

Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...

. He was appointed as a court physician at the age of 29. He wrote a number of medical texts, but his most significant achievement is Dongui bogam, which is often noted as the defining text of Traditional Korean medicine

Traditional Korean medicine

Traditional Korean medicine developed with the influence of other traditional medicine. Its techniques in treatment and diagnosis are both similar and unique to other traditional medicine...

. The work spread to East Asian countries like China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, and Vietnam

Vietnam

Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 where it is still regarded as one of the classics of Oriental medicine today.