Where does “у” come from?

у (Tajik) comes from Classical Persian و, from Middle Persian 𐭠𐭥𐭣, from Old Persian 𐎢𐎫𐎠, from Proto-Indo-Iranian Hutá, from Proto-Indo-Iranian Hu, from Proto-Indo-European h₂ew, from Proto-Indo-European ǵʰe — Postpositional intensifying particle: indeed, at any rate, in fact.

Ancestry of “у”, step by step

StepLanguageWordMeaning
1Classical Persianو—
2Middle Persian𐭠𐭥𐭣—
3Old Persian𐎢𐎫𐎠and
4Proto-Indo-IranianHutá—
5Proto-Indo-IranianHu—
6Proto-Indo-Europeanh₂ewaway from, off; again
7Proto-Indo-EuropeanǵʰePostpositional intensifying particle: indeed, at any rate, in fact
Every word from Proto-Indo-European ǵʰe →Every word from Proto-Indo-European h₂ew →Every word from Proto-Indo-Iranian Hu →