Description
Sorry for I had to interrupt the scenario's development for about a week, work got in the way...
But it's back! I decided to use 's scenario and arrangement, it made more sense and ultimately it was more realistic (historically and geographically) than mine. These are ethnic and religious maps for the region, showing the divides between peoples and faiths of this alternate scenario.
Scenario (by , original map: lorec10.deviantart.com/art/Rom… )
The start is same as Dom-Bul 's: romanized peoples of Dacia migrate to western Balkans while southern Slavs settle to the east.
The latter ones know a sweeping process of diversification; apart for linguistic drift, these populations are also carved by religious matters, in fact around VIII-IX century peoples to the south are converted to Eastern Orthodox Church through the influence of Byzantium while the north is occupied by the Croatian Empire which stays loyal to Roman Catholic Church (an event which will be widely exalted at the end of XX century to counter alleged Serbian hegemony). Time flows, the Croatian Empire to the north and the Byzantine Empire to the south progressively lose power and by the end of the first millennia are in strong decline. This void of power doesn't stay unfilled for long though, both Bulgarians and Serbs will have the opportunity to create rapidly growing but ephemeral empires and kingdoms, the north will also be partially divided by other neighbors such as Hungarians, Kievans and Polish.
To the west, if Romanians initially know a period of alternating political autonomy they still have to front both Frankish and Byzantine Empires invasions in times of war, being able to enjoy, on the other hand, incomes of west-east land trades in times of peace, actually they even try to set up important market cities but they are sort of eclipsed by the growing power of Venice, the North Italian city actually begins to set control on Adriatic coast and sea trades reveals to be more profitable than roads-requiring land trades.
Moving on to following centuries, Byzantium falls in 1453 even though Turks Ottomans managed to land in Europe even before that date (as they did in OTL), the political fragmentation and instability of Balkan region ease the work to the Muslim conquerors, Austrians and Hungarians also profit of this situation and self ruled territories reduce faster and faster in the region. Ottomans set control up to OTL Walachia and southern Moldavia to the east and southern Serbia to the west (remember everything is inverted though). Their footprint on the Balkans is dramatic, to ensure defense they start to islamize indigenous people (molding Bosniaks) and settle in OTL southern Moldavia (molding Gagauz); in addition they islamize Albanians and settle in Bulgaria. Even cultures of the peoples under Ottoman rule which are not islamized are still heavily influenced by the Turks.
To counter Islam advance Austrians move their troops to north-west, they will annex lands until Drava and Sava rivers and create the Kingdom of Illyria further south, a puppet state inhabited by Romanians. Hungarians annex Transylvania, settling it partially. Despite this, the Turks manage to siege Vienna in 1529. A little kingdom forms to north-east, it is called the Kingdom of Nistria, from this moment on it will be long existing but for most of time it will be a puppet of surrounding empires (to begin with Ottoman which are the founders), Ottomans also grant independence to the Kingdom of Montenegro, transforming it into a puppet as well.
Apart for the success of Christian Kingdoms to push back the Ottomans to previously quoted borders, the Balkan region doesn't know many changes until the XIX century, sure, all the powerful rulers existing in the region start to inexorably decline (with the remarkable rise of the Russian Empire), but we have to wait until that century to really start to see major geopolitical changes. It is in fact with the arrival of French revolution political values that the national identities of Balkan peoples start to (re)emerge and the first to experience the consequences of this are the Ottomans, the sickest of all. In two "Balkan wars" their European possessions are wiped out and to their place a number of nation-states are born also thanks to the help of Russians (Romania and Albania to the east, Serbia and Bulgaria to the west, Greece to the south).
But the newly formed Austro-Hungarian Empire stays strong to the north, and even annex the Bosnia-Gagauzia region. At this point hatred towards this empire is spread in the Balkans and in 1914 the prince dauphin is shot in Iaši (a multiethnic and multi religious city, capital city of Bosnia-Gagauzia) by a member of a Serbian terrorist organization. It is war, World War One. The result is in favor of Balkan indigenous peoples which all gain independence. Serbia manages to annex Montenegro and Catholic territories to the north, forming the Kingdom of Serbs, Croats and Nestrians (renamed Yugoslavia later). Romania unite to the west, including Dalmatian inhabited areas. Wartime is not over yet though, after a couple of decades World War Two also comes. Germans, Italians and Hungarians lead the invasion of the Balkans. In northern Yugoslavia an independent puppet state for Croats and Nestrians is formed, led by the Ustaša. Romania is also partitioned and made a puppet of Italy and Germany.
Finally World War Two is also over. Yugoslavia is restored but under a communist regime, while Romania gains Istria but manages to stay neutral.
After the fall of communist bloc Yugoslavia violently dismembers while Romania has to give up Kosovo region following major riots. Most countries have already joined EU in 2013, some are still candidate to do so.
Original idea is not mine. First suggestion of this scenario here: lorec10.deviantart.com/art/A-c…