It did not develop exclusively from high German, as I wrote before and it was geographically widespread enough for clear Eastern vs Western dialects to emerge:

It did not develop exclusively from high German, as I wrote before and it was geographically widespread enough for clear Eastern vs Western dialects to emerge: https://en.wikipedia.org/wiki/Yiddish_dialects#Eastern_Yiddish https://en.wikipedia.org/wiki/Yiddish_dialects#Eastern_Yiddi... Rather than existing "in the area we would now call west Germany" as you would like to believe for some reason. Eastern Yiddish in particular is much more than "a German language" (unless you want to call Polish a German language as well).