It is not clear whether he was descendant of
Pinsk–
Turaŭ or
Kingdom of Galicia–Volhynia branch of the
Rurik dynasty. Some scholars claim that his grandfather was
Vasylko Romanovych, Prince of
Slonim and direct descendant of
Roman of Galicia, others however claim his origin in line of
Sviatopolk II of Kyiv and suppose that his father was Danylo.
Kasper Niesiecki, an 18th-century writer, reported that "
Danylo Vasyliovych, son of Danylo of Galicia`s brother, first started to call himself Prince of Ostroh". He could be also direct grandson of Danylo of Galicia and son of Mstyslav Danylovych.
Adam Naruszewicz wrote that Danylo Ostrozky was
starost of
Przemyśl, officer of
Casimir III the Great when he inherited Galicia after the death of
Boleslaw-Yuri II of Galicia. Danylo was probably only temporary supporting King Casimir, because in 1344 he called the
Tatars to fight for Galicia in the
Galicia–Volhynia Wars, like
Dmytro Dedko who died in the same year. Finally Prince Danylo allied to
Liubartas who also rivaled for Galicia with Tatars, Poles and Hungarians. He received
Ostroh from Liubartas,
King of Galicia–Volhynia, ==See also==