Where does “nechein” come from?

nechein (Middle High German) comes from Old High German nihein, from Proto-Germanic nehw ainaz — nor one.

Ancestry of “nechein”, step by step

Step	Language	Word	Meaning
1	Old High German	nihein	no
2	Proto-Germanic	nehw ainaz	nor one

nechein — Etymology, Origin & Word History | Etymology Explorer