Where does “Starobilsk” come from?

Starobilsk (English) comes from Ukrainian Старобі́льськ, from Ukrainian стари́й, from Old East Slavic старъ, from Proto-Slavic starъ, from Proto-Balto-Slavic staʔros, from Proto-Indo-European steh₂-ro-, from Proto-Indo-European steh₂- — to stand.

Ancestry of “Starobilsk”, step by step

Step	Language	Word	Meaning
1	Ukrainian	Старобі́льськ	—
2	Ukrainian	стари́й	old, ancient
3	Old East Slavic	старъ	—
4	Proto-Slavic	starъ	old
5	Proto-Balto-Slavic	staʔros	—
6	Proto-Indo-European	steh₂-ro-	large, big, thick; old
7	Proto-Indo-European	steh₂-	to stand

Every word from Proto-Indo-European steh₂- →Every word from Proto-Indo-European steh₂-ro- →Every word from Proto-Balto-Slavic staʔros →