The Byzantine Empire

The eastern roman empire would effectively be the entity which we refer to as the byzantine empire going forward. The romans had waged war with the imperial movements of the lands of persia, firstly, with the parthians and then their successors. But an arab kingdom based in the hejaz began to draw neighboring lands into its imperial reach. This islamic caliphate wiped sened persia off the map and took the levantine and north african lands of the byzantines. And this would teach them they were not strong enough to have a mediterranean empire.