So that's how the Dál Fiatach helped maintain their economy ... and their over group the Ulaid more importantly! I often wondered why they didn't completely collapse in the face of Uí Néill domination, (remember, the Ulaid once controlled all of Ulster) but I guess this must have significantly aided them. Just by the way, the Dál Riata were a neighbour group of the Dal Fiatach allied to them through the overgroup of the Ulaid, and through migrations over the years ended up controlling Western Scotland as well as a part of North Eastern Ireland. Today, after generations of cultural mixing between themselves and the Picts, they are simply known as "Scots".
But ... the term NI has no place here.