Among Koreans with this surname, the largest clan is the Jeju Go clan [ko], named for its bon-gwan (clan hometown) of Jeju Island; they claim descent from Go Eul-na [ko], the first ruler of the kingdom of Tamna, which ruled Jeju until being absorbed by the Joseon dynasty.
[1][2] According to the Samguk Sagi, the Goguryeo royal family claimed descent from the mythical god Gao Yang, who was the grandson of the Yellow Emperor of Chinese mythology, and thus took the surname of "Go" (高);[3][4][5][6][7][8] however, this legend was discredited in the commentaries (논찬; 論贊) by Kim Busik, the compiler of the Samguk Sagi, who concluded that both Baekje and Goguryeo originated from Buyeo.
In South Korea, Hoengseong Go clan is also descended from the Royal dynasty of Goguryeo and the clan's genealogy book specifies Dongmyeong of Goguryeo as the direct ancestor.
[10] According to the 2000 South Korean census, there were 435,839 people in 135,488 households with this surname.
[11] In a study based on a sample of applications for South Korean passports in 2007, 67.5% chose to spell it as Ko, 18.3% as Go, and 11.4% as Koh.