Gerhart was subject to King Louis the Pious and ruled the shire-county Westergoa.
[1] Hugo Jaekel used the Traditiones et Antiquitates Fuldenses, the Annales Fuldenses and other historical documents from the Abbeys of Fulda, Werden, and Corvey to hypothesize that Gerhart and the line of Counts of Friesland were descended from Redbad, King of the Frisians.
Jaekel places Gerhart as son of Gerulf I of Frisia and father of Wigging.
Shortly after Gerhart's death, his eldest son, Folkger, did not accept the title.
[2][3] Gerhart, his son Wigging, and other nobility from the region gave land and goods from several pagi of Friesland to the Abbey of Fulda.