Cruthin

[8] Ancient Greek geographer Pytheas called the Celtic Britons the Pretanoí, which became Britanni in Latin.

[16] The Cruthin still held territory west of the Bann in County Londonderry, and their emergence may have concealed the dominance of earlier tribal groupings.

[17] In 563, according to the Annals of Ulster, an apparent internal struggle amongst the Cruthin resulted in Báetán mac Cinn making a deal with the Northern Uí Néill, promising them the territories of Ard Eólairg (Magilligan peninsula) and the Lee, both west of the River Bann in County Londonderry.

The same year, the Cruthin king Mael Caích defeated Connad Cerr of the Dál Riata at Fid Eóin, but in 637 an alliance between Congal Cláen and Domnall Brecc of the Dál Riata was defeated, and Congal was killed, by Domnall mac Aedo of the northern Uí Néill at Mag Roth (Moira, County Down), establishing the supremacy of the Uí Neill in the north.

The Annals record a battle between the Cruthin and the Ulaid at Belfast in 668, but the last use of the term is in 773, when the death of Flathruae mac Fiachrach, "rex Cruithne", is noted.

[23] Possible linguistic connection between Cruthin and Picts is nevertheless mentioned in St. Andomnán's Life of St. Columba (c. 697-700 AD), in which it is stated that Columba needed to speak through an interpreter on his mission into Pictland (section XXXIII) (signifying that he could not understand the Pictish language), and that he brought with him two Irish Cruthin (St. Comgall and St. Canice) to translate for him.

Dál Riata was a Gaelic kingdom that included parts of western Scotland and northeastern Ireland.

[11] In the 1970s, Unionist politician Ian Adamson proposed that the Cruthin were a British people who spoke a non-Celtic language and were the original inhabitants of Ulster.

[27][28] Prof. Stephen Howe of the University of Bristol argues it was designed to provide ancient underpinnings for a militantly separate Ulster identity.

[31] Much of Adamson's theories are based on the historical model put forward by Irish linguist T. F. O'Rahilly in 1946.

[33] There is a lack of archaeological evidence for O'Rahilly's theory, and it was conclusively shown to be false in the landmark 2017 publication of the "Irish DNA Atlas",[34] which sets out in great detail the genealogical history and modern day makeup of the British Isles.

[35] Robert E. Howard's pulp hero Bran Mak Morn was characterised as "chief of the Cruithni Picts".