It is well within the time period: (from wikipedia below)
Silesia has historically been an ethnically diverse region. Germanic tribes were first recorded within Silesia in the 1st century. Slavs arrived in this territory around the 6th century.The first known states in Silesia were those of Greater Moravia and Bohemia. In the 10th century, Mieszko I incorporated Silesia into the Polish state. In this state it remained until the Fragmentation of Poland. Afterwards it was divided between Piast dukes, descendants of Władysław II the Exile, High Duke of Poland.
In the Middle Ages, Silesia was divided among many independent duchies ruled by various Silesian dukes of the Piast dynasty. During this time, cultural and ethnic German influence increased due to immigrants from the German-speaking components of the Holy Roman Empire. Between the years 1289–1292 Bohemian king Wenceslaus II became suzerain of some Upper Silesian duchies. Silesia subsequently became a possession of the Crown of Bohemia under the Holy Roman Empire in the 14th century.
It happened during the middle ages. Silesia was a mix of Poles, Czechs, Germans, and the mix their cultures created, a Silesian culture.
I believe the way the English culture change works is that if they have a ruler who is Frankish/Norman they change from Anglo-saxon to English culture.
Why could it not work any differently for Silesia, which has a historic precedent for being a melting pot of cultures?
Also, the reason I suggested magyar is because Polish and Bohemian are in the same culture group. If Polish was lechitic and Bohemian west slavic this would be different.
For the Czechs I would do this; and I say thins knowing that the next eight posts will be a nationalistic nightmare, but this is how MEIOU works:
Culture groups are a
game mechanic and must be used as such. The Czechs tended to play nice with the Germans in the HRE... hell they were Emperor many times under the Luxemburg dynasty which definitely favored their Czech lands over their German lands. They shouldn't be "foreign" to the HRE, they should be a
central and respected part of the HRE. A Czech Emperor should not cause the HRE to fall apart due to a foreigner modifier.
Really, what I'd do with the Central German cultures is break them up into smaller groups: Dutch, Czech (move this in from West Slavic), Northern German, Middle German, Southern German. The different German groups don't need separate names but this will help represent the Imperial Circles a bit. Their aren't "foreigners"
per se, they just aren't one giant homogeneous blob of Germans. Hell, even in the age of unified language and mass culture the Germans
still aren't one giant homogeneous blob of Germans.
What this will do is make Bohemia more central to the HRE. They might get elected a bit more and they won't constantly try to break free simply because of a foreign ruler. It will also decentralize the Germans a bit more, hopefully like will vote for like and this will sort of be like the circuits that existed within the Empire.
Now, and I know this will stop no one so I will just switch voices here:
DON'T GO INTO NATIONALISTIC/LINGUISTIC DISCUSSIONS ABOUT THIS. If you have a legit
gameplay or
game mechanic reason please tell us. Or if you have a better idea, I love better ideas.
Ehem: I understand that Czech is not Germanic, I know the Czechs are Slavs closely related to the Poles and Sorbs. I understand that many people confuse the culture groups for linguistic groups. But they aren't. They are a game mechanic in a game which we are trying to balance. Dividing cultures purely on Linguistic lines and not on game balancing lines can be a real pain. Gigau has done a great job with MEIOU and every week or two we have to get out the game mechanic hammer and whack down the obnoxious honking of "The English aren't French" or "The Catalonians aren't Italian" "Burgundians aren't German", "Bulgarians and Greeks aren't Turkish". We know these things. But it means we can sculpt the AI, subtle nudges that avoid railroading the AI but guide them into historic expansion or behavior. I guess the best word is "plausible" behavior. Adding the Czechs to the Central Germanic group isn't about saying the Czechs are Germanic, or that they should be, or anything like that. It means that the Czechs should play nicely with the Empire because historically they did... and they were rewarded for it until the Hussite Wars (which were Holy Wars, not cultural ones). If it makes everyone happy rename "Central Germanic" to "Imperial" so it describes all the cultures that made up the core lands of the HRE (e.g. we wouldn't add the rebellious Italians here).
The best example, again from MEIOU, is with the Ottoman Empire. Initially, since the Turks were Turks and the Greeks were in a group with the Georgians and Armenians, the Ottomans never really expanded into Europe. We later noticed that they loved expanding eastward... into the Turkish lands beyond the Caspian. At first we added Bulgarian to the Turkish group and it distracted the Ottomans long enough to conquer a bit more of Europe but then inevitably went back to the Steppe. This isn't like in one or two games... this was a trend. The Ottomans ignored Constantinople for the wastes of the Steppe. So eventually, under much nationalistic protest, gigau made the "Byzo-Turkish" culture group. Greeks were no longer related to Armenians and Georgians, instead they were tied into the Bulgarians and Turks. And what happened? The Ottomans behaved more historically: they tried to take Constantinople. What if they failed? Well, sometimes the Byzantine Empire rose from the ashes and then tried to retake Anatolia. Things were
plausible. The Ottomans should not ignore Constantinople for the Steppe and the Byzantine Empire shouldn't ignore Anatolia for the Caucasus. In the same way the Czechs should be equals within the Empire, not just some foreigners who are waiting to escape.