It derives from the Chinese character 南宮.
In Korea, there are historically 6 Namgung Bon-gwan clans, including Hamyeol, Puyun, Nampyong, Ryongan, Uiryeong, and Chasan.
[1] Hamyeol Namgung clan claims ancestry from Nangong Kuo, a key adviser in King Wen of Zhou's court.
According to them, Namgung Su, a descendant of Nangong Kuo, came alongside Kija to Korea and helped him found Kija Joseon.
[2] In South Korea, statistics from 2000 indicate the Hamyeol Namgung clan has 18,703 members.