According to the Chuzan seikan (Mirror of the Ages of Chuzan) and the Omoro Soshi (Book of Poems), an official poetry compilation, which together are considered the official history of the Ryukyu islands, MINAMOTO no Tametomo escaped to the Ryukyus (Okinawa Prefecture), and his son took the name Shunten, the founder of the royal lineage of Ryukyu; however, the authenticity of this tale that Tametomo visited the Ryukyus cannot be verified.
琉球の正史である中山世鑑や公選の歌集であるおもろさうしでは源為朝が琉球（沖縄県）へ逃れ、その子が琉球王家の始祖とされる舜天になったとされているが、来琉の真偽は不明である。