Insular Celtic languages are the group of Celtic languages spoken in Brittany, Great Britain, Ireland, and the Isle of Man. All surviving Celtic languages are in the Insular group, including Breton, which is spoken on continental Europe in Brittany, France. The Continental Celtic languages, although once widely spoken in mainland Europe and in Anatolia, are extinct.
Six Insular Celtic languages are extant (in all cases written and spoken) in two distinct groups:
Breton (/ˈbrɛtən/, BRET-ən; French: [bʁətɔ̃]; endonym: brezhoneg [bʁeˈzɔ̃ːnɛk] or [bɾəhɔ̃ˈnek] in Morbihan) is a Southwestern Brittonic language of the Celtic language group spoken in Brittany, part of modern-day France. It is the only Celtic language still in use on the European mainland.
Breton is an Insular Celtic language that was brought from Great Britain to Brittany by migrating Britons during the Early Middle Ages, making Breton most closely related to Cornish, another Southwestern Brittonic language. Welsh and the extinct Cumbric, both Western Brittonic languages, are more distantly related, and the Goidelic languages (Irish, Manx, Scottish Gaelic) have a slight connection due to both of their origins being from Insular Celtic.
The Picts were a group of peoples in what is now Scotland north of the Firth of Forth, in the Early Middle Ages. Where they lived and details of their culture can be gleaned from early medieval texts and Pictish stones. The name Picti appears in written records as an exonym from the late third century AD. They are assumed to have been descendants of the Caledonii and other northern Iron Age tribes. Their territory is referred to as "Pictland" by modern historians. Initially made up of several chiefdoms, it came to be dominated by the Pictish kingdom of Fortriu from the seventh century. During this Verturian hegemony, Picti was adopted as an endonym. This lasted around 160 years until the Pictish kingdom merged with that of Dál Riata to form the Kingdom of Alba, ruled by the House of Alpin. The concept of "Pictish kingship" continued for a few decades until it was abandoned during the reign of Caustantín mac Áeda.
Pictish society was typical of many early medieval societies in northern Europe and had parallels with neighbouring groups. Archaeology gives some impression of their culture. Medieval sources report the existence of a Pictish language, and evidence shows that it was an Insular Celtic language related to the Brittonic spoken by the Celtic Britons to the south. Pictish was gradually displaced by Middle Gaelic as part of the wider Gaelicisation from the late ninth century. Much of their history is known from outside sources, including Bede, hagiographies of saints such as that of Columba by Adomnán, and the Irish annals.
Pictish was the extinct Brittonic Celtic language spoken by the Picts, the people of eastern and northern Scotland from late antiquity to the Early Middle Ages. Virtually no direct attestations of Pictish remain, short of a limited number of geographical and personal names found on monuments and early medieval records in the area controlled by the kingdoms of the Picts. Such evidence, however, shows the language to be an Insular Celtic language – possibly a variant of the Brittonic language once thought to be spoken in most of Great Britain.
The prevailing view in the second half of the 20th century was either that Pictish was a non-Indo-European language isolate, or that there coexisted not one but two Pictish languages: one Indo-European (Brittonic Celtic branch) and the other non-Indo-European.