I haven't read the book but Toaff is differentiating them from the already established Italian Jews. The German Ashkenazis were recent arrivals and were double outsiders, forming a separate ethnic and linguistic group that was resented by (and distinct from) the Jews who were already there.

I had a quick skim and it's an extremely detailed work of scholarship that paints a vivid portrait of life at the time. At some point I'll go through it and read it properly.