Could a Pontic-Caspian horde, a Slavic migration, or later Bulgaria or Serbia have pulled it off? What would the implications be for post-Byzantine history, and especially Balkan ethnic identities?
Conditions: Constantinople falls to a group who do not consider themselves Greek, whose power base is in the Balkans or Pontic steppe, permanently dismantling (or at least permanently disabling) the East Roman / Byzantine Empire - analogous to OTL 1453.
Conditions: Constantinople falls to a group who do not consider themselves Greek, whose power base is in the Balkans or Pontic steppe, permanently dismantling (or at least permanently disabling) the East Roman / Byzantine Empire - analogous to OTL 1453.