 The Irish historian Seán Duffy suggested that this " Mac Somhairle " was Domhnall mac Raghnall . Duffy 's main argument is that the 17th @-@ century Book of Clanranald relayed a tradition that Domhnall had been invited by the Irish at Tara to come " to take the headship of the Western Isles and the greater part of the Gaels " . 
