Hey ty - Look what I found.
http://cla.calpoly.edu/~mriedlsp/His...Maps/map2.html
This map is more subdivided than most than I have seen. I think you will notice that the political divisions of Europe after WWI looked a lot more like this map than before.
Plus I think you will notice that the changes in this ethnolinguistic map, since it was created, were done by Stalin's ethnic cleansing. At this point the ethnic lines were pretty set except where Stalin messesd with them. Germans no longer in Pomrania, Silesia and Konigsburg. Modern Poland, although not conforming to this map, is almost all Polish today because of Stalins ethnic cleansing. The other interesting thing to notice is that ethnic Ukrainians encompassed all of Ukraine and even some of western Russia. Where now Eastern Ukraine is full of Russians and Eastern Russia has no Ukranians. Another result (I think) of Stalin's ethnic cleansing.
It is also interesting to note (as Less pointed out) that Serbocroatia is considered one ethnic group where France is not. Also many people consider the different dialects of Italy (Tuscan, Milanese, Napolese) are more disctine from eachother than French dialects. The makers of this map didn't seem to think so.
One clear error on this map is showing the Czech area as solidly Czech. I know the Sudatenland, which is labelled as ethnically Czech was like 97 percent German.