The Principality of Volhynia may have emerged as early as the late 10th century, with Vsevolod, a son of Vladimir I of Kiev, mentioned as a prince of the city of Volodymyr.

[12] In part, this was because land trade routes in Asia Minor were severely disrupted due to the Byzantine–Seljuk wars (1046–1243),[13] diverting numerous merchants coming from the east heading for Constantinople via Alexandria in Egypt, while others circumvented Anatolia via the port of Sudak (Sougdaia) in Crimea.

[14] The flourishing of the latter commercial hub soon attracted Kievan Rus' traders, who rerouted some of the would-be Byzantine goods (occasionally through itinerant Jewish merchants) to Poland, Hungary, Bohemia and Germany, via the towns of Volhynia and Galicia.

[15] Their new status as transit hubs for commerce between the northern Black Sea ports and central Europe brought Galicia and Volodimer-in-Volhynia tremendous wealth and increasing political power in the late 12th century.

[12] This happened when the local Galician branch of the Rostislavichi clan died out, and Roman Mstislavich of Volhynia also took possession of Galicia, establishing a dynastic union.

[citation needed] Roman was allied with Poland, signed a peace treaty with Hungary and developed diplomatic relations with the Byzantine Empire.

[citation needed] Roman was subsequently killed by Polish forces in the Battle of Zawichost (1205),[18][19] triggering a war of succession, while his dominion entered a period of rebellion and chaos that lasted almost 40 years.

[18][20] In this time, the Galician boyars made efforts to prevent the establishment of a hereditary princely dynasty, especially by Roman's son Daniel, and instead put all sorts of puppets on the throne which they could easily control.

[18] Thus weakened by war between Galician boyars and some appanage princes, Galicia–Volhynia also became an arena of rivalry between Poland and Hungary, which intervened in the region several times.

[20] During Mstislav's 1221–1228 reign, the Galician and Volhynian armies participated in the Battle of the Kalka River (1223) against the Mongols, but in 1228 the boyars expelled him and transferred the Principality of Galicia to the king of Hungary.

[20] After failing to retake his father's other throne in 1230–1232 and 1233–1235, Daniel succeeded upon his third attempt and conquered Galicia in 1238, reunited Galician and Volhynia, and ruled for a quarter century.

[citation needed] Daniel strengthened his relations with Batu Khan by traveling to his capital Sarai and acknowledging, at least nominally, the supremacy of the Mongol Golden Horde.

[26] He did renew his alliances with Hungary, Poland and Lithuania, making plans to forge an anti-Mongol coalition with them to wage a crusade against the Khan; although these were never carried out, it would eventually lead to Daniel's royal coronation by papal legate in 1253.

[citation needed] Daniel was crowned by the papal legate Opizo de Mezzano in Dorohochyn 1253 as the first King of Ruthenia (Rex Russiae; 1253–1264).

[28] Upon the approach of a large army under the Mongolian general Boroldai in 1260; however, Daniel was forced to accept their authority and to raze the fortifications he had built against them.

Galicia–Volhynia was important enough that in 1252, Daniel was able to marry his son Roman to Gertrude of Babenberg, heiress of the Duchy of Austria, in the vain hope of securing the latter for his family.

[citation needed] After Daniel's death in 1264, he was succeeded by his son Leo, who moved the capital from Chełm to Lviv in 1272 and for a time maintained the strength of the Kingdom of Galicia–Volhynia.

From 1274 to 1276 he fought a war with the new Lithuanian ruler Traidenis but was defeated, and Lithuania annexed the territory of Black Ruthenia with its city Navahrudak.

In 1279, Leo allied himself with king Wenceslaus II of Bohemia and invaded Poland, although his attempt to capture Kraków in 1280 ended in failure.

[citation needed] His encouragement of foreign colonization led to conflicts with the boyars, who then poisoned him in 1340 and offered the throne to Liubartas, within the same year Casimir III of Poland attacked Lviv.

[citation needed]The Romanovichi (branch of the Rurikid) dynasty of Daniel of Galicia attempted to gain support from Pope Benedict XII and broader European powers for an alliance against the Mongols, but ultimately proved unable to compete with the rising powers of the centralised Grand Duchy of Lithuania and the Kingdom of Poland.

The first stage of conflict led to the signing of a treaty in 1344 that secured the Principality of Peremyshl for the Crown of Poland, while the rest of the territory belonged to a member of the Gediminid dynasty of Liubartas.

[citation needed] Following the death of Casimir the Great in 1370, Galicia–Volhynia was ruled by Vladislaus II of Opole in 1372–1379 and 1385–1387, as Lord of Ruthenia (Terre Russie Domin), being a descendant of princes of Belz and a subject of King Louis I of Hungary.

In contrast, the Westerners faced by Alexander, prince of Novgorod, were the Teutonic Knights, and the northeastern Rus experience of the West was that of hostile crusaders rather than peers.

[28] In Ukrainian historiography, the Kingdom of Galicia-Volhynia played an important role, uniting the western and southern branches of East Slavs and consolidating their identity, and becoming a new center of political and economic life after the decline of Kiev.