Eystein Halfdansson was the son of Halfdan Hvitbeinn of the House of Yngling according to Norse tradition.
He inherited the throne of Romerike. Ari Thorgilsson in his Íslendingabók calls him Eystein Fart without comment, in his king list, just... Wikipedia
Born: 725 AD, Norway
Died: 750 AD (age 25 years), Rygge Municipality, Norway
Parents: Halfdan Hvitbeinn
Great grandchildren: Halfdan the Black, Olaf Geirstad-Alf, Bruno the Young, and more
Great-grandparents: Ingjald and Gauthildr Algautsdóttir
Grandchildren: Gudrød the Hunter, Hasela von Sachsen, Sigurd, 5th King of Haithabu, and more
Grandparent: Olof Trätälja