A number of Roman legionnaires and officials decided to stay in Britain after their service had ended.
When the Roman’s finally withdrew, these Romano-British took control of the island.
In 425 AD, a Roman British aristocrat called Vortigern became leader of the British.
He then made a decision which was to have enormous consequences:
He invited a Germanic tribe called the Jutes, from modern day Denmark, to settle on British soil.
(Above) A reconstruction of the famous helmet of an Anglo-Saxon king, found at the Sutton Hoo ship burial site.
Vortigern wanted their help in fighting the un-Romanised Celts in the north of the island, the Picts.
Vortigern told the chief of the Jutes, called Hengist, that if they would help him fight the northern Celts, they would be given land in south-eastern England, modern day Kent.
Vortigern’s plan backfired badly when the Jutes brought with them a huge number of their fellow Germanics tribes, including Saxons, Angles, Franks, Frisians and other tribes.
Very soon war broke out between the Romanised British Celts and these Germanic newcomers.
The war raged for ten years and by the year 452 AD Vortigern had been defeated by Hengist.
These Germanic tribes then started to expand in Britain, occupying all of modern England.
(Above) Map showing the major Germanic invasions of the British Isles. The coming of the Anglo-Saxons, as they became known, caused the division within Britain between Celtic Cornwall, Wales, Scotland and Ireland, and Anglo-Saxon England, a division that has persisted until the present day.
The Germanic invaders, the Angles and Saxons, gradually became known as the Anglo-Saxons, and gave their name to what is know modern day England (Angle-land).
Although large numbers of Romanised Celtic British did get pushed into the fringes of modern Britain – Cornwall, Wales and Scotland – the incoming Germanic invaders did not have, as previously thought, such an overwhelming genetic effect on the native British population.
They did however dominate completely in a cultural and political sense.
Some of these Romanised British Celts even fled across the English Channel to what is now Brittany, giving their name to that region in modern day France.
Towards the end of the 5th Century, native Celtic resistance towards the incoming Anglo-Saxons increased.
Around this time there emerged a famous legend of a British Celtic king called Arthur, and his Knights of the Round Table.
The legend was built up mainly by story-telling, but it eventually became a central part of British folklore.
(Above) Map showing the major Anglo-Saxon kingdoms. Each kingdom took turns appointing a supreme king called a Bretwalda, who acted as overlord of the whole of Anglo-Saxon Britain.
The coming of the Anglo-Saxons meant that, once again, the former Roman area of Britain, what is modern England, reverted back to paganism, with Christianity being forced into the outer reaches of the British Isles.
The Anglo-Saxons then setup separate kingdoms, each with its own monarchy: Kent, Sussex, Wessex, Essex, East Anglia, Mercia and Northumbria.
It became tradition for these major Anglo-Saxon kingdoms to take turns in designating a supreme king, or Bretwalda (Britain Wielder), to serve for a while as overlord of Anglo-Saxon Britain.
When the last invasions of the Germanic tribes ceased, the Christian Church, with its headquarters in Rome, started to send missionaries to Britain once again.
When one of the Bretwaldas, King Ethelbert of Kent, married a Frankish Christian princess, she persuaded him to allow the missionaries back into the country.
In 597 AD King Ethelbert officially converted to Christianity and very soon Christianity spread rapidly amongst the nature worshipping pagan Anglo-Saxons.
By 664 AD the very last Anglo-Saxon kingdom, Northumbria under King Oswy, converted to Christianity and that religion became dominant throughout the whole British Isles.