Consider these two maps of the Roman Empire in 330, plus some important info on the first three Justinian emperors. We can discern the following:
- The Eastern Roman Empire is a mostly Greek-speaking empire since forever (read: Alexander the Great), but its northwesternmost territory is Latin-speaking. The majority of Latin-speaking Byzantines were from northern Thrace and North Macedonia, with a smaller proportion hailing from modern-day Montenegro, south Serbia etc.
- The first Byzantine emperor who spoke Greek as his native language was Tiberius II Constantine, according to Edward Gibbon. His three predecessors – Justin I, Justinian I, and Justinian II – all spoke Latin as their mother tongue. Justin I was, indeed, a Thraco-Roman by birth, and his birth name was Istocus (Istok in Thracian). He and Justinian I were both born in modern-day Skopje, North Macedonia.
The easiest solution would simply be to have Italy and/or North Africa remain part of the ERE, but I am not interested in either; I'd like the ERE to more-or-less retain its position as an empire in the Balkans and in Anatolia, and I also still plan to make Italy go through similar circumstances as IOTL (Pope, city-states, division, Charlemagne, you get the idea), while also still allowing Spain and Portugal to exist.
Thus, the easy way out is not what I'm looking for. What I want instead is for this Slavic raiding of Macedonia and Thrace, which IOTL exterminated the remaining Thraco-Romans and their settlements, to be stopped or minimized, so that the Latin Thracian culture and people live on instead of being lost to history. Of course, it's not just as simple as "ooga booga the slavs are repelled forever". This is undeniably going to have consequences, especially if Bulgaria isn't established at all. Furthermore, I can't imagine that repelling the Slavs would be an easy task, since if it was, the Romans would've just done that IOTL.
With all this in mind:
- What method do you think is best for preserving Latin in the Byzantine Empire, WITHOUT making them rule Italy or North Africa? Is it a good solution to keep Thrace/Macedonia Latinized, by repelling the Slavs or limiting their damage? If not, is there another method?
- What would the ramifications be of an ERE that keeps Thrace intact? Would a Bulgarian Empire even be able to exist here? And if not, surely there are some nasty butterfly effects and consequences for European history, no? If so, what could these be?