He was, according to the author of the Vita Sadalbergae, an "illustrious man (vir inluster), opulent in wealth and fame according to the highest secular dignity and skilled in courtly affairs."
It was probably created by Dagobert I in order to defend southern Austrasia from the Alemanni and to assert Austrasian claims to the region in the face of Burgundian opposition.
Between 629 and 631, Gundoin removed Sadalberga, already a widow, from her convent of Remiremont and sought to marry her to a courtier of Dagobert I, Balduin Baso, at the king's insistence.
The monks, under Germanus, built a monastery and cleared an old Roman road which lay on the shortest route from Basel to Biel.
Gundoin has controversially been identified with Gunzo, a duke in the region around Lake Constance with his seat at Überlingen, who betrothed his daughter to Sigebert III.