Where does “زنجیر” come from?

زنجیر (Persian) comes from Sanskrit शृङ्खल, from Proto-Indo-European ḱer-, from Proto-Indo-European kr̥-, from Proto-Indo-European ker- — army.

زنجیر (Persian): chain

Definitions

Step	Language	Word	Meaning
1	Sanskrit	शृङ्खल	chain, fetter, especially one made of iron;...
2	Proto-Indo-European	ḱer-	to grow, to make grow, to nourish; to plait,...
3	Proto-Indo-European	kr̥-	to turn, to bend
4	Proto-Indo-European	ker-	army

زنجیر — Etymology, Origin & Word History | Etymology Explorer