I am asking about lower class rural population, I know that German was spoken in cities. There already exists maps which shows some details on the matter:
- Map about german language extention
- Map about proportion of german speakers in each Silesian districts
We can see a very clear language barrier between Breslau and Oppole, unfortunately the first map is not precise enough to show where exactly the limit was. The second map show districts, but does not show the language barrier between different villages within a district, so we cannot see exactly which villages are on each side of the former language barrier.