The High Medieval praise poem Duan Albanach names Dúngal the Impetuous, and claims that he ruled for seven years.
It seems that Dúngal's father had finally managed to defeat his rivals shortly before he abdicated.
While Dúngal was no longer king of Dál Riata after 726, it may be that he remained ruler of the Cenél Loairn.
In 731, he burned Tairpert Boitir, most probably Tarbert on Loch Fyne which was in the lands of the Cenél nGabráin and possibly a portage site.
In 733 the Annals of Ulster report that Dúngal profaned Tory Island by forcibly removing Bruide, who is presumed to be the son of Óengus mac Fergusa, king of the Picts.