The Roman Empire in the Middle Ages

The roman empire didn't collapse wholesale. It retrenched in the east. barbarian tribes, tribes without illiterate culture made incursions into roman territory. Byzantium had lasting implications all the way through the middle ages. The first arab caliphates have very strong claim themselves to be considered inherent estates of rome. And we're going to be looking in broad strokes at the barbarian kingdoms, the retrenched byzantium and the arab conquests which dramatically changed the landscape that had once been a Roman world.