According to the 2015 South Korean census, the population of the Haengju Gi clan was 27,379.
Their founder was Gi U-sŏng [ja] who was a descendant of Jun of Gojoseon, the last king of Gija Joseon.
U-seong was the eldest son of Hun who was the 7th descendant of Jun.
U-sŏng's two younger brothers, U-ryang and U-pyŏng, became the progenitors of the Han and Sunwoo families respectively.
[1] Gi U-sŏng was Gija’s 48th generation descendant.