Where does “داغ” come from?

داغ (Classical Persian) comes from Proto-Indo-European dʰégʷʰeti — to burn, to be burning.

Ancestry of “داغ”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	dʰégʷʰeti	to burn, to be burning

داغ — Etymology, Origin & Word History | Etymology Explorer