Gija Joseon
There is a controversy on where Gija is from, which is believed to be from the Chinese Shang Dynasty, Gija as a paternal uncle (or brother) of the last emperor of the Chinese Shang Dynasty, King Zhou, however Gija is likely a Dongyi, a native people in the fast east. Gija's and his descendants were also believed to have the surname Han (韓) as King Jun of Gojoseon the last King of Gojoseon and descendant of Gija claimed himself as the King of Han (한왕; 韓王) with the foundation of Mahan part of the Samhan after fleeing from Wiman. With this it shows that the surname Han may have existed since the time of Gija Joseon or Gojoseon and establishes the Han (韓) clan as the oldest surname in Korea dating back to around 5000 years ago, and to have founded and ruled Gojoseon and Mahan.