"Silesia" in Polish is "Slask".
Silesia is constantly being Polonized to the day?
Hmm - how it can be Polonized since it belongs to Poland? Castles still stand there because they are HISTORICAL monuments - most of them cannot be ruined under the penalty of law.
I'll ask my friend who is a historian to give you a more precise answer though :).As promised, here is the experts opinion:
From the early twelfth century, the Polish lords of these vast territories began to attract new colonists with the promise of collective and individual exemptions from dues and services and the prospect of the lighter burdens in the future.
The settlement of the east Elbians lands developed into major enterprise, as entrepreneurs and speculators, locators , looked to enrich themselves by the provision of human capital -migrants!!! From Franconia, Saxony, and the Low Countries- to landowners , desperate for the manpower without even the most extensive estates were useless.
The ruling elite of the Polish territories were anxious to attract settlers , or as they were styled 'guest', hospitia's a recognition of the need to regard them as 'free' men. The hospities brought with them new, more compact field systems and technical innovations in the form of mills, and heavier ploughs. In 1175, Duke Boleslaw 'the Tall' (1163-1201) of Silesia allowed German Cistercians to settle colonists at Lubiaz, on the Oder, exempting them from 'Polish Law'-they were to remain free from the normal dues, services and burdens which a Polish prince might choose to impose on his subject.
A much more systematic and intensive program of colonization under 'German law', ius teutonicum, was developed in Silesia by Boleslaw's son , Henry 'the Bearded' (1201-38)'German law' meant not the laws of Germany , but the more or less standard package of terms under which colonists from the Germans lands were settled east of Elbe and Oder rivers. West of Elbe , the bulk of the peasantry remained closely tied to their lords -unless they broke loose and made the difficult decision to settle in the east on more generous terms, albeit under , harsher physical conditions.
When , in 1129 , Henry the Bearded began to run out freshly assimilated Germans, he took, to locating Polish migrants under 'German law'. Other lords, dukes and ecclesiastics followed the suit. There were some compensations-German law , actually restricted the terms on which settlers might leave, by comparison with more open-ended Polish practice. By the middle of the fourteenth century , if not earlier , the bulk of the Polish peasantry , including a largely assimilated element , could regard themselves as in some sense 'free'.
But assimilation worked both ways . By the end of the thirteenth century, in central and northern Silesia, the more fertile areas most attractive to the new settlers have become German, rather then Polish. By 1300 , the once Polish village of Wlen , near Wroclaw, has become the German Lahn, and Wroclaw itself , to increasing numbers of its inhabitants, has been becoming "Breslau."
That is how germanisation of Silesia slowly followed.