His foreign policy tended towards the alliance with the kings of Hungary and Poland, and against the Grand Princes of Kiev, who supported Yaroslav's cousin Ivan Berladnik in his attempts to take possession of several towns bordering Volynia.

This situation, holding out the alarming prospect of Andronikos making a bid for Manuel's throne sponsored by both Galicia (Halych) and Hungary, spurred the Byzantines into an unprecedented flurry of diplomacy.

He fell in love with one Halychian woman, named Anastasia (also called Nastasia), took her as a concubine, repudiating his lawful wife Olga, the daughter of Yury Dolgoruky, in 1172.

He bequeathed his throne to a natural son by Anastasia (Oleg, sardonically called Nastasyich by the populace), while the lawful heir Vladimirko had to content himself with Przemyśl for the beginning.

Yaroslav is mentioned in the text as a powerful and respected potentate: Osmomysl's remains found their final resting place only recently after long period of disturbance.

Trying to secure his archaeological artifacts from ancient Halych and drawings of the cathedral in Krylos before the Soviet occupation of Western Ukraine, Jaroslaw Pasternak hid them in an undisclosed location shortly after he emigrated to Germany,[dubious – discuss] where he died without disclosing the secret place.