Ancient States of the British Isles: Map & History

In 43 AD, the Roman Empire invaded Britain. The British tribes opposed the Roman legions for many decades, but by 84 the Romans had decisively conquered southern Britain and had pushed into Brittonic areas of what is now northern England and southern Scotland. During the same period, Belgic tribes from the Gallic-Germanic borderlands settled in southern Britain. Caesar asserts the Belgae had first crossed the channel as raiders, only later establishing themselves on the island. In 122 the Romans fortified the northern border with Hadrian's Wall, which spanned what is now Northern England. In 142 Roman forces pushed north again and began construction of the Antonine Wall, which ran between the Forth–Clyde isthmus, but they retreated back to Hadrian's Wall after 20 years.

From Wikipedia: Celtic Britons · History: Roman conquest (CC BY-SA 4.0)

The Britons spoke an Insular Celtic language known as Common Brittonic. Brittonic was spoken throughout the island of Britain (in modern terms, England, Wales, and Scotland) and the Isle of Man. According to early medieval historical tradition, such as The Dream of Macsen Wledig, the post-Roman Celtic speakers of Armorica were colonists from Britain, resulting in the Breton language, a language related to Welsh and identical to Cornish in the early period, which is still used today. Thus, the area today is called Brittany (Br. Breizh, Fr. Bretagne, derived from Britannia).

From Wikipedia: Celtic Britons · Culture: Language (CC BY-SA 4.0)

In 43 AD, the Roman Empire invaded Britain. The British tribes opposed the Roman legions for many decades, but by 84 the Romans had decisively conquered southern Britain and had pushed into Brittonic areas of what is now northern England and southern Scotland. During the same period, Belgic tribes from the Gallic-Germanic borderlands settled in southern Britain. Caesar asserts the Belgae had first crossed the channel as raiders, only later establishing themselves on the island. In 122 the Romans fortified the northern border with Hadrian's Wall, which spanned what is now Northern England. In 142 Roman forces pushed north again and began construction of the Antonine Wall, which ran between the Forth–Clyde isthmus, but they retreated back to Hadrian's Wall after 20 years.

From Wikipedia: Celtic Britons · History: Roman conquest (CC BY-SA 4.0)

The Britons spoke an Insular Celtic language known as Common Brittonic. Brittonic was spoken throughout the island of Britain (in modern terms, England, Wales, and Scotland) and the Isle of Man. According to early medieval historical tradition, such as The Dream of Macsen Wledig, the post-Roman Celtic speakers of Armorica were colonists from Britain, resulting in the Breton language, a language related to Welsh and identical to Cornish in the early period, which is still used today. Thus, the area today is called Brittany (Br. Breizh, Fr. Bretagne, derived from Britannia).

From Wikipedia: Celtic Britons · Culture: Language (CC BY-SA 4.0)

Cnut died in 1035, precipitating a succession crisis as the throne was disputed between Harold Harefoot and Harthacnut. Harthacnut was unable to come to England as he had to deal with a threat to his position in Denmark, and Harald became king. When he died in 1040, Harthacnut was able to take over as king. He quickly became very unpopular, especially for imposing high taxes. The following year Edward the Confessor was invited to return from exile in Normandy and was recognised as heir to the throne. He succeeded when Harthacnut died in 1042.

From Wikipedia: History of Anglo-Saxon England · England under the Danes and the Norman Conquest (978–1066): Edward becomes king (CC BY-SA 4.0)

The last Roman ruler of Britain, the self-proclaimed Emperor Constantine III, moved Roman forces based in Britain to the continent. The Romano-British citizens reportedly expelled their Roman officials during this period and never again re-joined the Roman Empire. Apparently taking advantage of the lack of organised military, the Chronica Gallica of 452 reports that Britain was ravaged by Saxon invaders in 409 or 410. Writing in the mid-sixth century, Procopius states that after the overthrow of Constantine III in 411, "the Romans never succeeded in recovering Britain, but it remained from that time under tyrants".

From Wikipedia: History of Anglo-Saxon England · Rapid cultural change (400–550 AD) (CC BY-SA 4.0)