Britain between the years ad 300 and 700 was on the edge of a fragmenting Roman world. Much of the indigenous population had been under Roman rule with Hadrian's Wall acting as the frontier of Britain and the Roman Empire. The Introduction outlines the shape of Britain at the start of the Anglo-Saxon age. Torn between the pagan barbarian north and the Christian Roman south, Britannia became a melting pot of many different influences. It is this diversity and ambiguity that help explain the distinctiveness of the early medieval cultures that would create the Britain of later years.