Eochaid Mumho was a legendary High King of Ireland. The office of High King of Ireland (Irish: Ard Rí Érenn) was in origin a pseudohistorial construct of the eighth century that placed a king of all Ireland atop the fragmented pyramid of kingship that actually existed at that time. ...
The High Kingship of Ireland was a pseudohistorical construct of the eighth century AD, a projection into the distant past of a political entity that did not become reality until the ninth century. ... Signature page from the Annals of the Four Masters Entry for A.D. 432 The Annals of the Four Masters or the Annals of the Kingdom of Ireland by the Four Masters are a chronicle of medieval Irish history. ... Seathrún Céitinn, known in English as Geoffrey Keating, was a 17th century Irish clergyman, poet and historian. ... Aengus Olmucada, son of Fiacha Labhrainne, was a legendary High King of Ireland. ...
Eochaid or Eochadha was often anglicized as Oghy or Oghie.
Eochaid Salbuide (yellow-heel), Eochaidh of the festive horns (from The Geste of Fraoch)
Another candidate is Eochaid, son of Connlai, King of Ulidia from about 526 to 548 (or 553), who was, according to all the annalists, the founder of the tribe of Ui Echach Ulad.