Erc was king of Irish

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 Dál Riata

Dál Riata

Dál Riata was a Gaelic overkingdom on the western coast of Scotland with some territory on the northeast coast of Ireland...

 until 474. He was the father of Fergus Mór

Fergus Mór

Fergus Mór mac Eirc was a legendary king of Dál Riata. He was the son of Erc.While his historicity may be debatable, his posthumous importance as the founder of Scotland in the national myth of Medieval and Renaissance Scotland is not in doubt...

 and Loarn mac Eirc

Loarn mac Eirc

Loarn mac Eirc was a legendary king of Dál Riata who may have lived in the 5th century.The Duan Albanach and the Senchus Fer n-Alban and other genealogies name Loarn's father as Erc son of Eochaid Muinremuir...

, and may have been the great-grandfather of Muirchertach mac Muiredaig

Muirchertach mac Muiredaig

Muirchertach mac Muiredaig , called Mac Ercae, Muirchertach Macc Ercae and Muirchertach mac Ercae, was said to be High King of Ireland. The Irish annals contain little reliable information on his life, and the surviving record shows signs of retrospective modification...

. Confusion arises from the latter's matronym, Macc Ercae, said to come from his legendary mother Erca, daughter of Loarn mac Eirc. She married Muiredach mac Eógain

Muiredach mac Eógain

Muiredach mac Eógain was a King of Ailech and head of the Cenél nEógain branch of the northern Uí Néill. He was the son of the founder of this dynasty Eógan mac Néill ....

. According to the Duan Albanach

Duan Albanach

The Duan Albanach is a Middle Gaelic poem found with the Lebor Bretnach, a Gaelic version of the Historia Brittonum of Nennius, with extensive additional material ....

 and the Senchus Fer n-Alban

Senchus fer n-Alban

The Senchus Fer n-Alban is an Old Irish medieval text, believed to have been compiled in the 10th century. It may have been derived from earlier documents of the 7th century which are presumed to have been written in Latin...

 Erc of Dál Riata's father was Eochaid Muinremuir. They may have been descendants of Conaire Cóem.

Suggestions that he was identical with Muiredach mac Eógain and thus belonged to the Uí Néill

Uí Néill

The Uí Néill are Irish and Scottish dynasties who claim descent from Niall Noigiallach , an historical King of Tara who died about 405....

 are based on late sources, such as the Annals of the Four Masters

Annals of the Four Masters

The Annals of the Kingdom of Ireland or the Annals of the Four Masters are a chronicle of medieval Irish history...

. In fact the Dál Riata are considered Érainn or Darini

Darini

The Darini were a people of ancient Ireland mentioned in Ptolemy's 2nd century Geography as living in south Antrim and north Down...

 and claimed to be descendants of the famous Érainn king Conaire Mór

Conaire Mor

Conaire Mór , son of Eterscél, was, according to medieval Irish legend and historical tradition, a High King of Ireland. His mother was Mess Búachalla, who was either the daughter of Eochu Feidlech and Étaín, or of Eochu Airem and his daughter by Étaín...

. It is typical in late genealogies for unrelated peoples or those only related through marriage to be worked into a single genealogical scheme and all be made descendants of the same legendary founder.

Erc is significant as he has been traditionally regarded as the ancestor, through his son Fergus Mor, of the kings of Dalriada

Dalriada

Dalriada can refer to:* Dál Riata, a Gaelic kingdom in western Scotland and north-east Ireland in the Early Middle Ages* Dalriada School, a co-educational, voluntary grammar school in Ballymoney, Northern Ireland* Dalriada , Hungarian folk metal band...

, and through them the Kings of Scotland, but more recently much of this tradition has been questioned.