Polovtsy is a name used to refer various Turkic tribes living to the East of Kievan Rus. I wonder at what point those Turkic peoples became Muslim?
The Cumans, with the Turko-Mongols, adopted Islam, in the second half of the 13th and the first half of the 14th century. **Wikipedia asserts that Cumans is one of a number of synonyms for Polovtsy
The cited article repeats the claim
In the second half of the 13th and the first half of the 14th century the Cumans, together with the Tatars, adopted Islam.