The name of Rademon townland 'Deammán's fort' in the Kinelarty part of Kilmore contains a significant secular reference. Deammán (OIr. Demmán) was an early chieftain of Dál Fiatach, referred to in the Ulster genealogies and in the Life of St Mochoemog (latinised Pulcherius): castellum Rath-temayn in quo erat rex Ulltorum 'the castle of Rath-temayn in which was the king of the Ulstermen'.
Castle Radaman was shown on the Down Survey map (EA 216).
Rademon is one of several place-names which record the names of lords and families of Dál Fiatach, the ruling tribe in east Ulster before the Normans.
St Dónart (OIr. Domangart) from whom Slieve Donard is named was a 6th-century member of this group, and Deammán was his cousin.
Lecale is named from 'Cathal's half' of their territory. Duneight 'Eochaid's fort' and Lissue 'Aed's fort' near Lisburn are named after a 9th-century king and his son, while Benmadigan 'Madudán's peak' commemorates kings in the 9th and 10th centuries.
he districts of Glengormley 'Gormfhlaith's offspring', and Blathewick 'descendants of Bláthmac' (Newtownards) were areas inhabited by families of the group at the time the Normans arrived.
A text of the genealogy was first published by Bishop Reeves (EA).--- from: placenamesni.org
After a reign of fourteen years, he was slain, A. D. 565, by the shepherds of Boirinnin. He married Garbae Ingine Néilléne. Demmán mac Cairill (died 572) was king of the Dál Fiatach, and high-king of Ulaid. He was the son of Cairell mac Muiredaig Muinderg (died 532), a previous Ulster king and brother of Báetán mac Cairill (died 581). He ruled the Dál Fiatach and Ulaid from 557 to 572. According to the genealogies, he was fostered by a certain Domangart mac Predae, possibly Domangart Réti, King of Dál Riata. He acquired the kingship of Ulaid by defeating and slaying Fergnae mac Oengusso Ibdaig at the Battle of Druim Cleithe (Kilclief, modern County Down) and had the support of the Uí Echach nÁrda (a branch of the Dál Fiatach). He was married to Garbae ingine Néilléne of the Cenél nEógain. He had five sons including Fiachnae mac Demmáin (died 627), a later king of Ulster. His descendants the Clan Demmáin went on to monopolize the kingship of the Dal Fiatach.