Yiddish follows the same pattern as other Jewish languages, ie. starting out as a sociolect of the local language with additional Hebraic vocabulary for subject

Yiddish follows the same pattern as other Jewish languages, ie. starting out as a sociolect of the local language with additional Hebraic vocabulary for subject matters specific to Jews. It doesn't seem any less German than say Austro-Bavarian. In any case I've heard from the mouths of Yiddish-speaking Polish Jews who had been through the Nazi concentrationary system that they in some respects had an easier navigating it than Western or Greek Jews because they spoke "more or less German".