Saxon southern England or Wessex, all areas south of a line through the current M4 and including Kent but excluding Cornwall which remained unconquered and Celtish.
The remainder of eastern and northern England was ruled by the Danish Vikings.
That is commencing in London, east of the river Lea and Lea Marshes and running north south through present day Wathamstow. This was a relatively stable division as the Saxon rulers in London persuaded the Danish Vikings to stay in their allocated territory in return for a regular monthly income of silver pennies minted in London.
Hence the area north of the Thames was approximately ½ mile north south and just over a mile east west.
Walking west from present day St Paul's Cathedral the road drops away steeply to Ludgate Circus and it is easy to imagine a large river infront of you before the bank rises steeply on the other side to a road now called Fleet street.
Indeed the river is still flowing but in a tunnel under the street After only a few years of Roman occupation, when the town had no protective walls a local British Queen "Boudicca", from East Anglia, burnt the place to the ground!
After Boudicca, over the next 200 years the Romans built "Londinium" into a fortified city of considerable wealth and comfort covering an area of some 330 acres surrounded by a wall 20 feet high.
An easy passage by ship down the river Medway and up the Thames.
The Romans used London to bring in all their vital goods from the rest of their empire particularly of course military equipment.
They also imported bronze ornaments, pottery, glass and millstones.