When did the Brythons exist?

The Brythons existed 5th–6th centuries. On this map they are drawn AD 439–1235.

How large were the Brythons?

At their greatest extent drawn on this map, the Brythons covered about 208,000 km². That is the largest area the border data gives them across the years they are drawn, not necessarily their greatest extent in history.

Europe · The migration period

Brythons

5th–6th centuries

See it on the map → Wikipedia ↗

Existed: 5th–6th centuries
Shown on the map: AD 439–1235
Peak area: 208k km²
Region: Europe

Overview

The Britons (Brythons) were a Celtic people, not a single state. They were the Romano-Celtic inhabitants of Britain who, after the end of Roman rule (c. 410), faced raids from Picts, Scots (Irish), and Saxons and the beginnings of Anglo-Saxon settlement. Sub-Roman Britain fragmented into a patchwork of successor polities under local kings and, tradition says, a superbus tyrannus — the figure known as Vortigern, blamed for inviting Saxon mercenaries (Hengist and Horsa) who then revolted.

History

Our principal near-contemporary source is the monk Gildas, whose polemic De Excidio et Conquestu Britanniae (On the Ruin of Britain, c. 6th century) denounces the sins of British rulers and describes the Saxon revolt as divine punishment. Gildas names Ambrosius Aurelianus, a Romano-British leader "of the last of the Romans," who rallied resistance, and refers to a great British victory at the Siege of Mons Badonicus (Badon) — later attached, in the 9th-century Historia Brittonum and Geoffrey of Monmouth, to the legend of King Arthur (who does not appear in Gildas). The reliability of Gildas — vague on chronology and names — and the historicity of Arthur are perennial scholarly debates.

Decline and legacy

The Britons were gradually pushed west over the following centuries into Wales, Cornwall (Dumnonia), the "Old North" (Hen Ogledd, e.g. Rheged, Strathclyde), and across the sea to Brittany (Armorica). They preserved Celtic Christianity and the Brythonic languages (ancestors of Welsh, Cornish, and Breton). Their kingdoms in Wales and the north endured for centuries as distinct British successor states.

Common questions

What were the Brythons?: The Britons (Brythons) were a Celtic people, not a single state. They were the Romano-Celtic inhabitants of Britain who, after the end of Roman rule (c. 410), faced raids from Picts, Scots (Irish), and Saxons and the beginnings of Anglo-Saxon settlement.
When did the Brythons exist?: The Brythons existed 5th–6th centuries. On this map they are drawn AD 439–1235.
How large were the Brythons?: At their greatest extent drawn on this map, the Brythons covered about 208,000 km². That is the largest area the border data gives them across the years they are drawn, not necessarily their greatest extent in history.
Who ruled the Brythons?: Our principal near-contemporary source is the monk Gildas, whose polemic De Excidio et Conquestu Britanniae (On the Ruin of Britain, c. 6th century) denounces the sins of British rulers and describes the Saxon revolt as divine punishment.
How did the Brythons end?: The Britons were gradually pushed west over the following centuries into Wales, Cornwall (Dumnonia), the "Old North" (Hen Ogledd, e.g. Rheged, Strathclyde), and across the sea to Brittany (Armorica). They preserved Celtic Christianity and the Brythonic languages (ancestors of Welsh, Cornish, and Breton).

Sources

This compendium cites its sources once for the whole document rather than per territory. Its bibliography names the English Wikipedia articles for each territory and its key figures as the primary basis, with Encyclopædia Britannica, the World History Encyclopedia, and academic and primary sources — Jordanes, Procopius, Gregory of Tours, Bede, Ammianus and the Anglo-Saxon Chronicle, read through the secondary literature. The article this entry is anchored on:

Wikipedia — Britons (Celtic people) en.wikipedia.org/wiki/Britons_(Celtic_people)

This entry was last updated 27 September 2026.

This entry was researched and drafted with AI from the sources above, and has not been reviewed by a historian. How entries are made

Text available under CC BY-SA 4.0: reuse it with a credit to The World Through Time and a link to this page. Passages drawing on the Wikipedia articles listed above are also licensed CC BY-SA 4.0 by their contributors.

Border geometry for the map itself comes from Cliopatria v0.12 (Seshat Global History Databank, CC-BY-4.0).

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