What largely Christian areas in a. d. 600 had no Christian presence in a. d. 325

In 6th-century Christianity, Roman Emperor Justinian launched a military campaign in Constantinople to reclaim the western provinces from the Germans, starting with North Africa and proceeding to Italy. Though he was temporarily successful in recapturing much of the western Mediterranean he destroyed the urban centers and permanently ruined the economies in much of the West. Rome and other cities were abandoned. In the coming centuries the Western Church, as virtually the only surviving Roman institution in the West, became the only remaining link to Greek culture and civilization.

profound political, administrative, and social changes in the british isles.