In Irish mythology Cearmna Finn was joint High King of Ireland with his brother Sobhairce. Sobhairce ruled the northern half and Cearmna the south. They were the first High Kings of Ireland to come from the Ulaid. Although many of the manuscripts containing texts relating to Irish mythology have failed to survive, and much more material was probably never committed to writing, there is enough remaining to enable the identification of four distinct, if overlapping, cycles: the Mythological Cycle, The Ulster Cycle, the Fenian Cycle and the... 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 Ulaid, also known as the Ulaidh and the Ulad, are a people of Early Ireland who gave their name to the Irish Province of Ulster. ...

Their reign lasted 40 years. Cearmna was killed by Eochaid Faebar Glas, son of Conmael. Sobhairce was killed by Eochaid Mann of the Fomorians. In Irish mythology, the Fomorians (Irish Fomóire, Fomórach) or Fomors were a semi-divine race who inhabited Ireland in ancient times. ...

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. ...