Where does “поясный” come from?

поясный (Russian) comes from Russian по́яс, from Proto-Slavic pȍjāsъ, from Proto-Balto-Slavic *jṓˀstei, from Proto-Indo-European yeh₃s- — gird; belt, girdle.

Ancestry of “поясный”, step by step

StepLanguageWordMeaning
1Russianпо́ясbelt, girdle, band, waistband, cummerbund
2Proto-Slavicpȍjāsъgirdle
3Proto-Balto-Slavic*jṓˀsteito gird, to band
4Proto-Indo-Europeanyeh₃s-gird; belt, girdle
Every word from Proto-Indo-European yeh₃s- →Every word from Proto-Balto-Slavic *jṓˀstei →Every word from Proto-Slavic pȍjāsъ →