According to Gesta Danorum (book 7), by Saxo Grammaticus, Hring was the son of the Swedish king Ingjald (Ingild) and the maternal nephew of the Danish king Harald Wartooth. His father Ingjald had raped the sister of Harald, but the latter did not mind in order preserve the friendship with Ingjald. Ring fought with Harald Wartooth in the Battle of the Brávellir and became the king of Denmark as well. Saxo then describes the different subkings and their adventures. In book 9, he returns to Sigurd Hring as Siward, surnamed Hring, the father of Ragnar Lodbrok.
Read more about this topic: Sigurd Hring