Jeong (정/程), sometimes romanized Jung, Chung and Chong is a common Korean Surname which means 'journey or agenda' in Sino-Korean Language, similar to Chinese Cheng. This surname is the 31st most common surname in Mainland China and 75th most common surname in Korean Peninsula.
There are three different Chinese Characters which have the same meaning with Sino-Korean 'Jeong' which are 鄭 (State in Henan Province, PROC), 丁 (fourth of the ten Heavenly Stems; Chinese: Deng) and 程 (Journey). The number of Koreans who bear the surname of 程 are sixty-two times lesser than those who bear the surname of 鄭 and six times lesser than those who bear the surname of 丁.
The surname is coming from the name of the area of Cheng during the Shang dynasty (1766–1122 BCE). A high adviser who was a descendant of the legendary emperor Zhuan Xu was granted the fiefdom of this area, and his descendants adopted its name as their surname. In ancient China, Zhuan Xu, asked his two grandsons to be in charge of making sacrifices.
The older brother, Chong, had the title of Nan Zheng and was in charge of making sacrifices to the heaven. The younger brother, Li, had the title of Huo Zheng and was in charge of the earthly matters. The two brothers brought peace and regulations to the people, so that they could concentrate on making a living on the farm. The descendents of Chong and Li, held on to the assignments for generations. During the Zhou Dynasty, the descendents of Chong was awarded the kingdom of Cheng (east of Le Yang in Henan Province), and they began to bear the last name Cheng.
Back in Korea, there are 32,519 people in 10,220 families who bear the surname of Jeong, based on the 2000 Korean Republic Census - provided by Statistics Korea (통계청/統計廳/Tonggyecheong/KOSTAT). The Hanam Lineage, a clan which is originated from Henan Province, PROC is the most dominant among Jeong Clan where this lineage consists of 7,766 people in 2,355 families.
Hanam Jeong Clan or Henan Cheng Clan (하남정씨/河南程氏) was founded by Jeong Sa-jo a.k.a Cheng Sizu in Chinese (정사조/程思祖), 14th Generation Descendant of Cheng Hao a.k.a Jeong Ho in Korean (정호/程顥; 1032-1085) - a neo-Confucian philosopher who hailed from Luoyang City, Henan Province, Mainland China. Jeong Sa-jo lived during the reign of King Chungjeong Wang Jeo (1338-1352), 30th Monarch of Goryeo Dynasty. During the outbreak of Japanese Imjin Invasion (1592-1598), this clan showed their military finesse, defending Joseon Dynasty from Japanese Invading Forces.