05-14-2023-2344 - The Principality or, from 1253, Kingdom of Galicia–Volhynia[2] (Ukrainian: Галицько-Волинське князівство, romanized: Halytsko-Volynske kniazivstvo; Latin: Regnum Galiciae et Lodomeriæ), historically known as the Kingdom of Ruthenia (Old East Slavic: Королєвство Русь, romanized: Korolevstvo Rusĭ; Ukrainian: Королівство Русь, romanized: Korolivstvo Rus; Latin: Regnum Russiæ),[3]

The Principality or, from 1253, Kingdom of Galicia–Volhynia^[2] (Ukrainian: Галицько-Волинське князівство, romanized: Halytsko-Volynske kniazivstvo; Latin: Regnum Galiciae et Lodomeriæ), historically known as the Kingdom of Ruthenia (Old East Slavic: Королєвство Русь, romanized: Korolevstvo Rusĭ; Ukrainian: Королівство Русь, romanized: Korolivstvo Rus; Latin: Regnum Russiæ),^[3] was a medieval state in Eastern Europe which existed from 1199 to 1349. Its territory was predominantly located in modern-day Ukraine, with parts in Belarus, Poland, Moldova, and Lithuania. Along with Novgorod and Vladimir-Suzdal, it was one of the three most important powers to emerge from the collapse of Kievan Rus'. The main language was Old East Slavic, the predecessor of the modern East Slavic languages, and the official religion was Eastern Orthodoxy.

Roman the Great united the principalities of Halych and Volhynia at the turn of the 13th century. Following the destruction wreaked by the Mongol invasion of Kievan Rus' (1239 to 1241), Prince Daniel of Galicia and other princes of Rus' pledged allegiance to Batu Khan of the Golden Horde in 1246. The Polish conquest of the kingdom in 1349 led to it being fully absorbed by Catholic Poland.^[4] Upon annexing it, Polish king Casimir III the Great adopted the title of King of Poland and Ruthenia, and the territory was transformed into the Ruthenian Voivodeship (Latin: Palatinatus Russiae) in 1434.

Geographically, western Galicia–Volhynia extended between the rivers San and Wieprz in what is now south-eastern Poland, while its eastern territories covered the Pripet Marshes (now in Belarus) and the upper reaches of the Southern Bug river in modern-day Ukraine. During its history, Galicia-Volhynia was bordered by the Grand Duchy of Lithuania, the Principality of Turov-Pinsk, the Principality of Kiev, the Golden Horde, the Kingdom of Hungary, the Kingdom of Poland, Moldavia and the Monastic State of the Teutonic Knights. 

https://en.wikipedia.org/wiki/Kingdom_of_Galicia%E2%80%93Volhynia