The story of the Journey North of the the Dál Fiatach begins with three Righ Uladh. The first was Muiredach Muinderg (died 489) who was was a king of Uladh from the Dál Fiatach. He was the son of Forggo mac Dalláin and his sobriquet means red-necked. The other two were his sons Eochaid (died 509) and Cairell (died 532).
The Bodleian Annals (Tigernach) have an entry : "Death of Muredach Muinderg. Eochaid his son, King of Ulad." This is equated with the famous battle of Cell Osnad fought in 489 a.d. Muredach left five sons, "who divided their inheritance in Druimne Breag." ... The name "Rath Droma Breg" is given as the residence of one of the sons, Cairill.
Map of the ridges of Breagh with Collon and Monasterboice
Monasterboice - Late 5th century monestary founded by Saint Buithe
Eighteenth Century Map of Collon and Ardee
Cairell mac Muiredaig Muinderg (died 532) also Cairell Coscrach ("victorious") was a king of Ulaid from the Dál Fiatach. He was the son of Muiredach Muinderg mac Forggo (died 489) and brother of Eochaid mac Muiredaig Muinderg (died 509), previous kings. His accession date is given in the Annals of Tigernach in 509 and the accession of his successor in 532 This annal gives him a reign of 509-532. The Tripartite Life of St. Patrick has a story that Saint Patrick cursed the descendants of his brother Eochaid and gave his blessing to the descendants of Cairell. Cairell's descendants did monopolize the kingship. His known sons were Demmán mac Cairill (died 572) and Báetán mac Cairill (died 581), both kings of Ulaid.
- The Dál Fiatach: Margaret E. Dobbs - Ulster Journal of Archaeology, Third Series, Vol. 8 (1945), pp. 66-79
- Zeitschrift f. Celt. Philologie, xi, p. 324.