This idea came to me while reading on the history of the Maratha Empire in the Indian Subcontinent. Basically they shattered the Mughals and created a huge Hindu Empire in the 1700's only to be finally subdued by the British.
So I asked myself: what conditions would be necessary in order that something similar to what happened to the Mughals would happen to the Ottomans. For some reason the Ottomans break apart and slowly a lot of their territories are conquered by a Greek-Orthodox (i.e., "Rum", they would obviously will not be all ethnically Greek in the modern sense) dynasty in the 18th century, similar to how the Marathas managed to liberate (or is it "liberate"?) a whole lot of India.
Here's the problems. The geopolitics of the Indian Subcontinent are vastly different from Anatolia and the Balkans. Basically often shifting borders is not such a new thing in South Asia, because the geographic barriers are not enough to (completely) block invaders. On the other hand Anatolia and the Balkans are quite the impregnable fortresses, but it might be done.
In OTL Anatolia (the Asian side of Turkey up to the Taurus and Antitaurus Mountains; it includes Cappadocia, Kayseri and the Black Sea region, but excludes the regions further East, specifically the N Mesopotamian Plains; the Adana region is not geographically included, but we'll consider it part of Anatolia proper for expediency's sake) the Greek-Orthodox population ("Rum Milleti", often speaking Turkish, or Laz, or Amerian or Greek languages other than Demotic such as Cappadocian or Pontic; there were also Vlachs and Bulgarians in Anatolia) was at about or just below 30%. Or at least in the 15th century it was so. By the 1910's it dropped to about 18%.
In OTL Balkans, in the late 1800's, the Muslim population was a little above 40%, but I guess historically it had been lower.
So here's the challange: Have, in the 18th century, a Greek-Orthodox power native to the Balkans or Anatolia (created, perhaps, through some kind of revolt) or even the Danubian Principalities take over the Eastern Balkans, part of Greece and all of Anatolia including Cappadocia, Pontus and the Adana Region. (I'm not interested in the desert of Mesopotamia east of Kayseri or in the useless mountains of the western Balkans like Bosnia or Albania or Epirus or such.)
If you include something about the Prut River Campaign or the Patrona Halil revolt, great. If you include much chaos on the Ottoman side and perhaps and alt-Muhammad Ali type of Pasha revolting, great. (I was asking myself if some Yeniceri rebel exterminating the House of Osman might do the trick of breaking the whole thing apart. The Girays might not be accepted by everyone... Then again, one can never underestimate the admittedly corrupt but still formidable Ottoman bureaucracy - the Mughals had nothing of the sort, to my knowledge.)
You are allowed to play with demographics - I like that sort of thing. You can have a secondary much earlier POD which results in higher number of Orthodox people in Anatolia and lower number of Muslims in the Balkans. You could also have an alt-Great Serb Migration fleeing Catholics and not the Turks, and migrating into Anatolia instead of S Hungary. Or any other crazy idea. The whole thing is pretty crazy to begin with. (The idea is, after the thing is stable in the late 18th century there would be some Anatolian Highland Clearances. Perhaps after another war whith whatever Muslim power is left east, in mid 19th century the new Byzantines might try on the remaining Anatolian Turks what the Russians did to the Circassians. This is very unfortunate, but I'm not sure it can be avoided for a full restauration. In any event, it is fortunate that we're only going to look for now into the events up until the alt-Napoleonic Wars.)
I haven't though of what would happen after nationalism kicks in. Everyone will probably not be hellenised. But then again, with diverse enough populations... (all Jews in Israel speak the previously dead Hebrew so who knows what could be done -- if not perhaps there would be Bulgarian Nationalist revolts in Ankara in late 19th century...)
So I asked myself: what conditions would be necessary in order that something similar to what happened to the Mughals would happen to the Ottomans. For some reason the Ottomans break apart and slowly a lot of their territories are conquered by a Greek-Orthodox (i.e., "Rum", they would obviously will not be all ethnically Greek in the modern sense) dynasty in the 18th century, similar to how the Marathas managed to liberate (or is it "liberate"?) a whole lot of India.
Here's the problems. The geopolitics of the Indian Subcontinent are vastly different from Anatolia and the Balkans. Basically often shifting borders is not such a new thing in South Asia, because the geographic barriers are not enough to (completely) block invaders. On the other hand Anatolia and the Balkans are quite the impregnable fortresses, but it might be done.
In OTL Anatolia (the Asian side of Turkey up to the Taurus and Antitaurus Mountains; it includes Cappadocia, Kayseri and the Black Sea region, but excludes the regions further East, specifically the N Mesopotamian Plains; the Adana region is not geographically included, but we'll consider it part of Anatolia proper for expediency's sake) the Greek-Orthodox population ("Rum Milleti", often speaking Turkish, or Laz, or Amerian or Greek languages other than Demotic such as Cappadocian or Pontic; there were also Vlachs and Bulgarians in Anatolia) was at about or just below 30%. Or at least in the 15th century it was so. By the 1910's it dropped to about 18%.
In OTL Balkans, in the late 1800's, the Muslim population was a little above 40%, but I guess historically it had been lower.
So here's the challange: Have, in the 18th century, a Greek-Orthodox power native to the Balkans or Anatolia (created, perhaps, through some kind of revolt) or even the Danubian Principalities take over the Eastern Balkans, part of Greece and all of Anatolia including Cappadocia, Pontus and the Adana Region. (I'm not interested in the desert of Mesopotamia east of Kayseri or in the useless mountains of the western Balkans like Bosnia or Albania or Epirus or such.)
If you include something about the Prut River Campaign or the Patrona Halil revolt, great. If you include much chaos on the Ottoman side and perhaps and alt-Muhammad Ali type of Pasha revolting, great. (I was asking myself if some Yeniceri rebel exterminating the House of Osman might do the trick of breaking the whole thing apart. The Girays might not be accepted by everyone... Then again, one can never underestimate the admittedly corrupt but still formidable Ottoman bureaucracy - the Mughals had nothing of the sort, to my knowledge.)
You are allowed to play with demographics - I like that sort of thing. You can have a secondary much earlier POD which results in higher number of Orthodox people in Anatolia and lower number of Muslims in the Balkans. You could also have an alt-Great Serb Migration fleeing Catholics and not the Turks, and migrating into Anatolia instead of S Hungary. Or any other crazy idea. The whole thing is pretty crazy to begin with. (The idea is, after the thing is stable in the late 18th century there would be some Anatolian Highland Clearances. Perhaps after another war whith whatever Muslim power is left east, in mid 19th century the new Byzantines might try on the remaining Anatolian Turks what the Russians did to the Circassians. This is very unfortunate, but I'm not sure it can be avoided for a full restauration. In any event, it is fortunate that we're only going to look for now into the events up until the alt-Napoleonic Wars.)
I haven't though of what would happen after nationalism kicks in. Everyone will probably not be hellenised. But then again, with diverse enough populations... (all Jews in Israel speak the previously dead Hebrew so who knows what could be done -- if not perhaps there would be Bulgarian Nationalist revolts in Ankara in late 19th century...)