Gen-evolu allows us to see the distribution of family names in Germany both in modern times and during the peak of the third Reich in WW2, before Germany was affected with the ethnic cleansing of its former eastern provinces. Unfortunately this information is based on Telephone books and telephone was still a luxury in the 40s so most many people didn't have one, yet this information is better than nothing.
The Polish version of dynastree allows us to see name distribution in Poland in modern times. Is there a way to see a name distribution of Poland before the country moved 250km to the West and was ethnically cleansed?