Byzantium was the eastern part of the Roman Empire.
Everyone knows that here.

People often make the mistake of thinking that Byzantine equals Greek.
Byzantines spoke greek. They also followed the Orthodox Church which spoke Greek. Most nobillity was greek. Albanians were always revolting so they weren't exactly on with the program. When the slavs apeared as you said they were ruled by other(greeks) so yes you could say byzantium=greek. Moreover if you look at the time line Byzantium aws really small for the most part. In the end it was limited to Constantinople and different patches in Pelloponesus.

Climent, Naum, Angelariy and Gorazd did (they were also Slavs)
You can keep them. We don't really care . What's the point of writing so much about things that have nothing to do with what this thread was started for? Are trying to prove something? I'm not trying to be offensive, I'm just wondering why?