Suppose I were a child of Byzantine nobility, and I was being educated sometime around the year 1000 CE. Suppose I asked my tutors things like “Who are we? How did we get here? Why have we lost so much territory? Will we ever recover the far-off regions of Gaul or the Exarchate of Carthage?”

What would I be told about what happened to the Western Roman Empire? Presumably I would learn about Trajan. I would learn that he spoke Latin, but my own emperor Basil II, and the rest of my peoples, are speaking Greek. How would that transition be explained? For that matter, would I be taught that Basil II was somehow “in the same line” as Trajan and the others from those long distant days of the old Roman Empire?

If I asked my tutors, “But why was Britannia (to name just one example) lost to the Empire? What was the reason for it?”, how would they answer?

I’ve read that the Byzantines never called themselves that. As far as they were concerned, they were Romans, and no less true Romans as their ancestors. But surely they must have known that something had changed. How did they conceptualize their own transition from what they once were to what they are now (meaning, in my example, the people of Constantinople in 1000 CE)?