Cruthin

For the asteroid sometimes (incorrectly) identified as Earth's second moon, see 3753 Cruithne.

The Cruithne or Cruthin were a historical people known to have lived in the British Isles during the Iron Age.

According to T. F. O'Rahilly's historical model, the Cruithne were descended from the Priteni, who O'Rahilly argues were the first Celtic group to inhabit the British Isles, and identifies with the Picts of Scotland. They settled in Britain and Ireland between 700 and 500 BC. They used iron and spoke a P-Celtic language, calling themselves Priteni or Pritani, which is the origin of the Latin word "Britto" and the Old English words "Briton" and "British".

More recent theories though, supported by archaeological evidence, suggest that the Cruithne were a pre-Celtic people, and may have spoken a non-Indo-European language before the spread and dominance of Celtic culture in the British Isles. It is also suggested that these people were the descendants of the aboriginal neolithic people of the isles. Around 50 BC Diodorus wrote of "those of the Pretani who inhabit the country called Iris (Ireland)". The first reference to the name Pict is found in a Latin document dated 297 AD.

It should be noted that Pytheasis credited with first recording the local name of the islands, in Greek as Prettanike - apparently in connection with the Cornish region - which Diodorus later rendered Pretannia.

In Britain these Priteni were absorbed by later invaders and lost their cultural identity, except in the far north where they were known to the Romans as Picti, or “painted people,” on account of their practice of decorating their bodies with paint or tattoos (a practice which by then had died out among other Celtic tribes). In Ireland, too, the Priteni were largely absorbed by later settlers; but a few pockets of them managed to retain a measure of cultural, if not political, independence well into the Christian era. By then they were identified as Cruithne, P-Celtic linguistic descendants of the Priteni.

Among the Cruthnian tribes that survived were the Loíges and Fothairt in Leinster. The name of the first of these tribes - modernized as Laois - has been revived and given to one of the counties of Leinster (formerly known as Queen's County).

Cruithne is the name of the Picts in Scottish Gaelic.

The language of the inhabitants of the British Isles is called Cruithne in Jacqueline Carey's Kushiel's Legacy series.

The existence of the Cruthin in Ireland as a pre-Gaelic people has led some (particularly unionists) to advocate the theory that they were not, as many nationalists consider, a "non-native" people.