Two 13th-century writers relate folklore that derives Thorgil from the mating of a bear with a noblewoman.
In the 18th century, Danish historian Jakob Langebek suggested this bear story was allegorical, and that the brutish 'Wild' Björn, father of Thorgil, was a reference to Jomsviking brigand leader Styrbjörn the Strong (Styrbjörn Starke),[REF][REF] depicted by sagas as the son of Olaf Björnsson, king of Sweden [REF].