 There was also cultural diversity in other Roman-British towns, which were sustained by considerable migration, both within Britannia and from other Roman territories, including North Africa, Roman Syria, the Eastern Mediterranean, and continental Europe.Of Roman Britain's estimated 3 million population, the urban population was about 240,000 people, with Londinium having an estimated 60,000 people.Germanic (Frankish) mercenaries were employed in Gaul by the Roman Empire and it is speculated in a similar manner, Germanic immigrants to Britain arrived at the invitation of the ruling classes.