So after the Romans left, the new settlers were Northern Europeans from the land of the Jutes and Angles in modern day Denmark, Saxony in modern day Germany and the land of the Fresians in modern day Holland.
They were the original boat migrants, crossing the North Sea on small boats and landing in Eastern and Southern Britain in the 5th to 8th centuries.
This era is also referred to as the Early Medieval Period or Anglo-Saxon Period. The term "Dark Ages" is less commonly used by historians today because it implies a lack of progress or cultural sophistication.
The Anglo-Saxons ruled Britain for approximately 656 years, from roughly 410 AD (after the Romans withdrew) to 1066 AD (the Norman Conquest).
Why did they migrate?
The Anglo-Saxons migrated to Britain primarily due to a combination of 'push' factors in their homelands and 'pull' factors provided by Britain in the 5th century CE, following the end of Roman rule.
Key reasons for the migration include:
Push Factors
Environmental Pressures
Population Growth and Land Scarcity
Inter-Tribal Conflict/Wider Migrations
Pull Factors
Political Vacuum and Weak Defenses
Invitation as Mercenaries
Economic Opportunity
Mild Climate and Good Farmland
