The origin of a society that encompassed the maritime areas of Northern Ireland, as well as the maritime areas of Western Alba, under the same dynastic or political leadership, did not begin with Fergus Mhór mac Erc and his kinsmen. Similar entities had probably existed in the Mesolithic Era (8000 - 4500 BC), Neolithic Era (4500 - 2500 BC), Bronze Age (2500 - 500 BC) and, indeed, there is strong evidence that Fergus' ancestors had been present in Alba for as long as 400 years when he arrived. The exact date of the beginning of this ancient saga is lost in the misty tales of the “Tuatha De Dannan” and the “Áes Sídhe” of Irish legend, but both archeological and other evidence shows that migrations across the North Channel, in both directions, had ebbed and flowed at least since the coming of the Celts after 2000 BC. The Irish culture had usually been dominant of these societies, since Irish resources and populations had been greater. This disparity was also true when the Dál Riata settled in what is now known as Argyll. Their greatest resource was the sea, and those who succeeded there were skilled mariners.