When did the different Germanic Languages morph from separate Languages into different dialects of German?

by agentnola

I was thinking about this in geography class in which we talked about how languages split off through isolation and how they combine with interaction. and I wondered ¨At what point could a Prussian be able to understand a Bavarian, or at least see that they were speaking the same language¨

holytriplem

This chart might help you.

At what point could a Prussian be able to understand a Bavarian, or at least see that they were speaking the same language

I'm not sure what you mean by that question, to be honest. To some extent, a Prussian speaking High German can still understand a Bavarian. Please clarify what you mean.