Oleksandr Palii, A History of Ukraine, 22.01.2018
Principality of Galicia-Volhynia continued the statehood traditions of Kyivan Rus’ for a century. The same dynasty of the descendants of Mstyslav the Great continued to rule there.
In 1199 a Volhynian prince, Roman II Mstyslavovych (son of Mstyslav II of Kyiv, ruled in 1173-1205) finally united Volhynian and Galician principalities in one state. In 1203 he set his power also in Kyiv, Pereyaslav and Chernihiv and led many military campaigns against Cumans, Hungarians, Poles and Lithuanians. In 1205 he died in action fighting troops of Cracowian prince, Leszek Bialy.
His son, Danylo Romanovych (Daniel son of Roman, born in 1201) officially ruled in 1205-1264, but only in 1238 he succeeded in re-uniting the principality after long inner wars among local leaders supported from abroad. In 1240 he also set his power in Kyiv, wisely defended his land against Mongols, in 1245 he defeated Hungarian army near Yaroslav, and in 1253 was even crowned by Pope Innocent IV, becoming the first Ruthenian (Ukrainian) king.
So, since 1253 Principality of Galicia-Volhynia changed its name to Kingdom of Ruthenia (Королѣвство Русь in Ruthenian, or Regnum Russiae in Latin).
Seal of Yurii Lvovych (1301–1308).
Under ruling of king Lev Danylovych (Leo son of Danylo, 1264–1301, moved the capital of its state from Kholm to Lviv in 1272) and king Yurii Lvovych (George son of Lev, 1301–1308), Kingdom of Ruthenia became the most powerful state in Eastern Europe. Lviv, Kholm and other, new cities grew and trade flourished. Dozens of the charters written in Ruthenian (Ukrainian) have survived since those times. After another Mongol-Tatar attack on Kyiv in 1299, the metropolitan of Kyiv, who was Greek by birth, moved to Vladimir-on-Klyazma and Yurii Lvovych obtained the consent of Constantinople to establish the Halych (Galician) Metropoly in 1303.
The Black Madonna of Częstochowa, one of the most revered icons in Poland. King Lev Danylovych brought it to Belz (Lviv region) probably from Byzantium. After Poland occupied Galicia, the icon was taken to Czestochowa in southern Poland.
However, later both rulers of the kingdom, brothers Andrii Yuriiovych (Andrew son of Yurii) and Lev Yuriiovych (Leo son of Yurii), died in 1323, probably in one battle against the Mongols and Tatars, becoming the latest Ruthenian kings. Their death was disastrous for the Kingdom of Ruthenia. It lost its independence, after a long struggle, in 1349. Later, the lands of Kingdom of Ruthenia were occupied and divided up among its neighbors, Kingdom of Poland and Grand Duchy of Lithuania and Ruthenia, after a war that lasted for half a century. Poland seized all of Galicia and a part of the Volhynian lands with the cities of Belz and Kholm, while Lithuania took most of Volhynia with the cities of Volodymyr and Lutsk.