Where does “āγāz” come from?

āγāz (Sogdian) comes from Proto-Iranian *ā-, from Proto-Indo-European h₂éd — to, at.

Ancestry of “āγāz”, step by step

Step	Language	Word	Meaning
1	Proto-Iranian	*ā-	not, un-, non-; lacking, -less
2	Proto-Indo-European	h₂éd	to, at