Why weren't places like Milan, Poland and Magdeburg barely or not at all affected by the Black Death compared to their neighbours?
(link to a map showing areas affected by the Black Death: http://hosted.lib.uiowa.edu/histmed/plague/plaguemapnew.html )
There is technically always more to be said, but you may be interested in this extremely comprehensive answer by /u/mikedash that examines why people have an erroneous impression that Poland was spared by the plague:
Why did Poland have lower rates of Black Death than other European countries during the 1300s?