The story of Björn and his brothers, the sons of the Scandinavian king Ragnar Lodbrok, was retold in different versions throughout the Middle Ages. The "Tale of Ragnar's Sons" ("Ragnarssona þáttr") is an Icelandic Fornaldar Saga from about the 14th century that combines traditional Norse oral history with legendary themes. It states that Björn was the son of Ragnar and Aslaug and that his brothers were Hvitserk, Ivar the Boneless, and Sigurd Snake-in-the-Eye. The tale also tells of Björn's half-brothers Eric and Agnar.