Where does “です” come from?

です (Japanese) comes from Japanese である, from Japanese で, from Japanese ぜ, from Japanese ぞえ, from Japanese え, from Middle Chinese 衣.

です (Japanese): Polite form of だ , after uninflecting parts of...

Definitions

Step	Language	Word	Meaning
1	Japanese	である	To be: the copula, with the same function as だ ...
2	Japanese	で	at; with, by, using; indicating the following...
3	Japanese	ぜ	sentence-ending particle signifying emphasis,...
4	Japanese	ぞえ	—
5	Japanese	え	Alternative form of い
6	Middle Chinese	衣	—