The Yngvi reference article from the English Wikipedia on 24-Apr-2004
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Yngvi

Alternative: Yngve.

Yngvi was the progenitor of the House of Ynglings, a legendary dynasty of Swedish kings from whom the earliest historical Norwegian kings in turn claimed to be descended. Information on Yngvi varies in different traditions as follows:

(The Yngling Saga section of Snorri Sturluson's Heimskringla also introduces a second Yngvi son of Alric who is a descendant of Yngvi-Freyr and who shared the Swedish kingship with his brother Alf.)

Jacob Grimm in his Teutonic Mythology and many others consider it likely that the same figure lies behind Ing/Ingo/Ingui, the legendary eponymous ancestor of the Ingvaeones.