• General Notes

  Erc was king of Irish Dál Riada until 474. The Annals of the Four Masters imply Erc was the same person as Muirdeach son of Eogan son of Niall of the Nine Hostages, High King of Ireland at the end of the 5th century. Other reports imply he decended from an older royal family dating to Conaire Caem in the 2nd century. Both possibilities remain viable.
  
  Dál Riada began its separation from Ireland during Erc's reign. Its former provinces in Ireland, mostly in modern County Antrim, falling more in line with the High King of Ireland. Erc established his base in Scotland near the area called Argyll, which means 'coastline of the Gaels.'
  
  Erc was probably the father of Fergus Mor, king of Dál Riada, though his immediate succesor was Loarn, a kinsman who probably succeeded through the tanistry law. Assuming Erc was a member of Niall's family, he would also be of the Uí Néill royal line, as would be his descendents. This is supported by his son, Muircheartach becoming High King of Ireland in 504.
  (Wikipedia)
  

Details of Erc's family with Marca