Origin of Name Bloch (Jewish version)
Bloch (Block) is very common among Jews. I am told that in Alsace it is as common as Smith in the US.
Remember that Alsace has gone back and forth from France to Germany about 2 or 3 times per century.Asatians speak French with a German accent.
During the late unpleasantness, many Alsatians considered themselves as German as their occupiers. Many Alsatian dishes are familiar to us as German dishes (e.g. Sauerkraut is known there as Choucrout pronounced "shoo crou".) So anything said about Alsatian Jewry counts as saying it about German, more or less.
Bloch is a corruption of the name Wallach.A simplified version of the corruption is that the Jews started out in Ger/Fr as Wallach.There was large scale (for the time) immigration to Poland in the late middle ages.While in Poland, Wallach was eventually changed into Bloch.They then travelled back to France and Germany and voi la(?).Ergo, a Polish connection to the French/German name Bloch.
If you are really serious in your question there are many fine books on Jewish genealogy available that discuss this very question.