Bolesław was born between 1305 and 1310 to
Trojden I of Masovia and Maria, daughter of
Yuri I of Galicia. Since his father was still a ruler of the family's Masovian lands, in 1323/1325 Bolesław succeeded
Leo II of Galicia and became the ruler over Ruthenia (Galicia and Volynia) as Yuri II. He also received the
Duchy of Belz after the childless death of
Andrew of Galicia. He used the titles of "Georgius Dei gratia Rex Russiae", "Georgius Dei gratia Dux Russiae", "Georgius Dei gratia Dux terrae Russiae, Galiciae et Ladimeriae". His candidacy (from a family of minor Masovian princes) pleased neighboring rulers (primarily the Tatar Khan), who did not see him as a competitor. Yuri II was a
Catholic by birth, but later converted to
Orthodoxy to avoid confrontation with the local aristocracy of Galicia and Volynia during his reign (the boyars resisted his rule). In 1324, Yuri granted city rights to
Volodymyr, where he established his court, and in 1339 granted
Magdeburg Law to
Sanok. The foreign policy of Yuri II was characterized by a balance in relations with the Kingdom of Poland, the Grand Duchy of Lithuania, Rome and the Tatars. However, Yuri II paid the greatest attention to relations with the Teutonic Order. In a 1325 charter, Yuri II promises the Grand Master of the Teutonic Order
Werner von Orseln to observe peace and friendship, "as our ancestors did: King Danylo, great-grandfather Lev, and dearest grandfather Yuri." In 1327, Yuri II concluded an alliance with the Teutonic Order and also granted permission to trade to Toruń merchants. Correspondence between Yuri II and Pope John XXII has also been preserved — the duke of Ruthenia pursued an active policy with Rome. In 1331, Yuri II achieved the restoration of the
Metropolis of Halych (which moscovian prince Ivan Kalita and Metropolitan
Theognostus tried to conquer) by the Patriarch of Constantinople
Isaias. In 1331, he married the daughter of
Grand Duke of Lithuania Gediminas and sister of
Aldona of Lithuania, wife of
Casimir III of Poland. The name of Bolesław's wife is disputed;
Teodor Narbutt claimed her pagan name was Eufemia and her Christian name was Maria. In opposition,
Oswald Balzer claimed that Eufemia was a Christian name. Yuri's murder sparked the
Galicia–Volhynia Wars fought in the years 1340–1392 over succession in the Kingdom of Ruthenia, which ultimately resulted in the kingdom ceasing to be an independent state, but instead being split between Poland (Galicia) and Lithuania (Volhynia). ==Ancestry==