Sub-Roman Britain in the context of "Gododdin"

King Arthur (Welsh: Brenin Arthur; Cornish: Arthur Gernow; Breton: Roue Arzhur; French: Roi Arthur) was a legendary king of Britain. He is a folk hero and a central figure in the medieval literary tradition known as the Matter of Britain.

In Welsh sources, Arthur is portrayed as a leader of the post-Roman Britons in battles against the Anglo-Saxons in the late-5th and early-6th centuries. He first appears in two early medieval historical sources, the Annales Cambriae and the Historia Brittonum, but these date to 300 years after he is supposed to have lived, and most historians who study the period do not consider him a historical figure. His name also occurs in early Welsh poetic sources, such as Y Gododdin. The character developed through Welsh mythology, appearing either as a great warrior defending Britain from human and supernatural enemies or as a magical figure of folklore, and was sometimes associated with the Welsh otherworld Annwn.

The historicity of King Arthur has been debated both by academics and popular writers. While there have been many claims that King Arthur was a real historical person, the current consensus among specialists on the period holds him to be a mythological or folkloric figure.

The first definite mention of Arthur appears circa 828 in the Historia Brittonum, where he is presented as a military leader fighting against the invading Saxons in 5th- to 6th-century Sub-Roman Britain at the Battle of Badon, more than three centuries before the work was written. Arthur developed into a legendary figure in the Matter of Britain from the 12th century, following Geoffrey of Monmouth's influential but largely fictional Historia Regum Britanniae.

The Romano-British culture arose in Britain under the Roman Empire following the Roman conquest in AD 43 and the creation of the province of Britannia. It arose as a fusion of the imported Roman culture with that of the indigenous Britons, a people of Celtic language and custom.

Scholars such as Christopher Snyder believe that during the 5th and 6th centuries – approximately from 410 when the Roman legions withdrew, to 597 when St Augustine of Canterbury arrived – southern Britain preserved an active sub-Roman culture that survived the attacks from the Anglo-Saxons and even used a vernacular Latin when writing.

Cornish people or the Cornish (Cornish: Kernowyon, Old English: Cornƿīelisċ) are an ethnic group native to, or associated with Cornwall and a recognised national minority in the United Kingdom, which (like the Welsh and Bretons) can trace its roots to the ancient Britons who inhabited Great Britain from somewhere between the 11th and 7th centuries BC and inhabited Britain at the time of the Roman conquest. Many in Cornwall today continue to assert a distinct identity separate from or in addition to English or British identities. Cornish identity has also been adopted by some migrants into Cornwall, as well as by emigrant and descendant communities from Cornwall, the latter sometimes referred to as the Cornish diaspora. Although not included as a tick-box option in the UK census, the numbers of those writing in a Cornish ethnic and national identity are officially recognised and recorded.

Throughout classical antiquity, the ancient Celtic Britons formed a series of tribes, kingdoms, cultures and identities throughout Great Britain; the Dumnonii and Cornovii were the Celtic tribes who inhabited what was to become Cornwall during the Iron Age, Roman and post-Roman periods. The name Cornwall and its demonym Cornish are derived from the Celtic Cornovii tribe. The Anglo-Saxon invasion and settlement of Britain starting from the late 5th and early 6th centuries and the arrival of Scots from Ireland during the same period gradually restricted the Romano-British culture and Brittonic language into parts of the north and west of Great Britain by the 10th century, whilst the inhabitants of southern, central and eastern Britain became English and much of the north became Scottish. The Cornish people, who shared the Brythonic language with the Welsh, Cumbrics and Picts, and also the Bretons who had migrated across the sea to escape the Anglo-Saxon invasions, were referred to in the Old English language as the "Westwalas" meaning West Welsh. The Battle of Deorham between the Britons and Anglo-Saxons is thought to have resulted in a loss of land links with the people of Wales.

British Latin or British Vulgar Latin was the Vulgar Latin spoken in Great Britain in the Roman and sub-Roman periods. While Britain formed part of the Roman Empire, Latin became the principal language of the elite and in the urban areas of the more romanised south and east of the island. In the less romanised north and west it never substantially replaced the Brittonic language of the indigenous Britons. In recent years, scholars have debated the extent to which British Latin was distinguishable from its continental counterparts, which developed into the Romance languages.

After the end of Roman rule, Latin was displaced as a spoken language by Old English in most of what became England during the Anglo-Saxon settlement of the fifth and sixth centuries. It survived in the remaining Celtic regions of western Britain. However, it also died out in those regions by about 700; it was replaced by the local Brittonic languages.

The Insular Celts were speakers of the Insular Celtic languages in the British Isles and Brittany. The term is mostly used for the Celtic peoples of the isles up until the early Middle Ages, covering the British–Irish Iron Age, Roman Britain and Sub-Roman Britain. They included the Celtic Britons, the Picts, and the Gaels.

The Insular Celtic languages spread throughout the islands during the Bronze Age or early Iron Age. They are made up of two major groups: Brittonic in the east and Goidelic in the west. While there are records of Continental Celtic languages from the sixth century BC, allowing a confident reconstruction of Proto-Celtic, Insular Celtic languages became attested only during the early first millennium AD. The Insular Celts followed an Ancient Celtic religion overseen by druids. Some of the southern British tribes had strong links with mainland Europe, especially Gaul and Belgica, and minted their own coins.

Prior to the 5th century AD, most people in Great Britain spoke a Brittonic language, but the number of these speakers declined sharply throughout the Anglo-Saxon period (between the 5th and 11th centuries), when Brittonic languages were displaced by Old English.

Debate continues over whether this change was due to mass migration or to a small-scale military takeover by people who spoke the West Germanic dialects that became Old English. The situation in post-Roman Britain was certainly strikingly different from, for example, post-Roman Gaul, Iberia or North Africa, where invaders speaking other languages gradually switched to local languages. This linguistic decline is therefore crucial to understanding the cultural changes in post-Roman Britain, the Anglo-Saxon settlement of Britain and the emergence of an English language.