Their Bon-gwan was in Seosan, South Chungcheong Province.
According to the research held in 2000, the number of Seosan Jeong clan was 15362.
Their founder was Jeong Eung chung [ja] living in Pujiang County, Zhejiang who was a government officer in Song dynasty.
Jeong Eung chung [ja] used to be a Yuanwailang (員外郎/员外郎).
Then, he settled in Seosan of Goryeo after Song dynasty declined.