Liubart Gediminovich – a descendant of the Grand Duke of Lithuania Gediminas. In 1323, after the death of Lev Yuriyovych of Halych, Liubart, according to the investigations of V. Antonovych, got Eastern Volyn as a son-in-law of the deceased, and still in the lifetime of his father moved to this region. After the death of Prince Yuri-Boleslaw II Trojdenovych of Halych-Volyn in 1340, the nobles announced Liubart, son-in-law of Yuri-Boleslaw, the Prince of Halych-Volyn. But Polish King Kazimierz II the Great immediately took the Peremyshl land and later seized Lviv. Since that time, Liubart came into a long-term conflict with Kazimierz for the patrimony of Halych princes. We do not know details of this strife, but from later annalistic sources we learn that Liubart managed to seize the towns of Volodymyr Volynsky, Kremenets, and Belz. When Kazimierz treacherously captured him, he was rescued with the help of the Grand Duke of Lithuania Kęistutis. He retained the towns he seized but had not enough power to take away Lviv and Peremyshl land from the Poles.
Kazimierz and Lithuanian princes, including Liubart, concluded a two-year armistice, which lasted approximately to 1347. In 1349 Kazimierz occupied Volyn, however, when he disbanded his troops and returned home, Kęistutis in alliance with Liubart expelled Polish garrisons from castles of Volyn, Kholm, and Belz lands, burst into the Lviv land and devastated Polish border regions. Lithuanian princes were invigorated by the rapprochement with the Grand Prince of Moscow Simeon the Proud: in 1349 with consent of the latter Liubart married (for the second time) Olga-Agafia (died after 1386), Simeon’s niece, daughter of Prince Konstantin Vasilyevich of Rostov. His first wife was possibly Yevfimiya (Busha-Agripina) (died before 1349), daughter of Lutsk Prince Lev Yuriyovych. Liubart had four sons: Fedir (ca 1351 – after 01.06.1431) – Grand Prince of Volyn (1383–1390, 1431), Siversk (1393–1405), and Zhydachiv (ca 1405–1431); Ivan (died in the late 14th c.); Lazar and Simeon (both died after 1386).
Volynian Prince Liubart became the progenitor of Sanguszko, Sanguszko-Koszyrski, andSanguszko-Kowelski families.
Under Liubart a fortress – the Liubart’s Castle – was built in Lutsk.