a Russian feudal principality that occupied the northeastern slopes of the Carpathian Mountains.
The Galician lands formed part of Kievan Rus’ in the tenth century. In the middle of the 11th century, they were among the possessions of Prince Vladimir Iaroslavich and then of his son Rostislav. The Galician princes joined forces with the Polovtsy (Cumans) and with Byzantium to fight for liberation from the rule of Kiev. Vladimir Volodarevich, who reigned from 1141 to 1153, united the Galician lands under his rule and became independent from Kiev. The Galician Principality flourished in the reign of his son Iaroslav Osmomysl (1153-87). After Iaroslav’s death, a decline in princely authority set in and the Galician Principality became less important. In 1199 the Volynian prince Roman Mstislavich took possession of the Galician Principality, which he merged with his own to form the Galician-Volynian Principality.