More info from professors at University of Leipzig:
Teschislav is the root form for Teclaw, which is the precursor for Tetzlaff . . . no dates given for the formation or progression of these names.
Confusing enough yet?No?
Well, Prof. Karlheinz Hengst informs me that although Teclaw and Teschislav are Lusatian (Sorbian) in origin, there are ALSO Czech and Polish originators as well.
So, depending on one's research and family line, one might get a different country of origin.I have a distinct feeling, though, that we're talking always about the same exact area of Europe, in general, that "right elbow" of E.Germany where it meets Cz.Republic and Poland.