In Serbia in middle ages, term "Romeji" (Romaioi) was used. Calling Roman Emperor in Constantinople a "Greek" was a good way to lose your head. Only the very last years of the Empire, when the Empire was even smaller then modern day Greece and was inhabited primarily by Greeks, hellenic heritage was accepted again.
I don't personally mind term Byzantine, as long as it is used to refer to the medieval Christian Eastern Roman Empire, not some imaginary country called Byzantium or even worse a Greek empire...
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