Cruthin

For the asteroid named for this people, see 3753 Cruithne.

The Cruthin or Cruithin (Old Irish: [ˈkɾuθʲinʲ]), later Cruithne (Irish: [ˈkɾˠɪ(h)nʲə]), were a people of early medieval Ireland. Their heartland was in Ulster and included parts of the present-day counties of Antrim, Down and Londonderry. Although the evidence is that they were Gaelic, their name is believed to be the Irish equivalent of *Pritanī, the reconstructed native name of the Celtic Britons, and Cruthin was sometimes used to refer to the Picts, but their relationship to these peoples is unclear. Based on their name, Kenneth H. Jackson suggested that the Cruthin descended from a group of Iron Age immigrants from Britain.

The Cruthin were first mentioned in the 6th century AD. They comprised several túatha (tribal territories), which included the Dál nAraidi of County Antrim and the Uí Echach Cobo of County Down. These were part of the kingdom of Ulaid (Ulster), although early sources distinguish between the Cruthin and the Ulaid folk. By the late 8th century, the annals had stopped using the term Cruthin in favour of the term Dál nAraidi, who had secured their over-kingship of the Cruthin. The 17th century Leabhar na nGenealach claims that the Conaille, the Loígis and the Sogain are also of Cruthin descent.

For political reasons, some modern Ulster Scots unionists claim descent from the Cruthin and argue they were the original British inhabitants of Ulster. This has been rejected by historians and archaeologists (see #Modern politics and culture).