In the early days of history (50-450) England was known as Britain and the people who lived there were the Britons. There were no big towns on the British Isles at that time. People lived in small villages along the rivers or near the sea. The Britons caught fish, grew wheat and had many pigs, cows and sheep in the meadows near the rivers and on the sides of the mountains. Later they learned to make things of wool and metal and sold them to the people who came across the sea.
The Romans with Julius Caesar at the head invaded the British Isles and forced the population to pay tribute.
The Romans kept their armies in Britain. They built roads and had the country under control.
They protected themselves from the attacks of the Britons by the walls which they built across Britain.
You can see the Roman walls in Britain even now. Here is Hadrian's Wall which was built by the emperor Hadrian in the year 122.
The Romans left the country only in the second half of the 5th century. The Roman armies were called back to Italy where they defended the country from barbaric peoples.