In Snorri Sturluson's Ynglinga saga, a part of the Heimskringla, he mentions the tradition of Halga, Eadgils and Yrsa, and he based his account on the Skjöldunga saga (he had access to the now lost original version).
He wrote that king Halfdan's (Healfdene) son Helgi ruled in Lejre. He invaded Sweden with such a large army that king Aðils (Eadgils) could not do anything else but to flee Uppsala. Helgi amassed a great deal of booty and took queen Yrsa (whom Aðils had found in Saxony) with him. Yrsa bore a son named Hrólfr Kraki (Hroðulf). When the boy was three years of age, Yrsa's mother, queen Alof of Saxony, came to visit her and told her that her husband Helgi was her own father. Then Yrsa returned to Sweden and king Aðils. Hrólfr Kraki was only eight years old when Helgi died during a war expedition, and Hrólfr was proclaimed his successor.
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