Ипатьевская летопись
The Hypatian Codex first mentions Ostroh in 1100, as a fortress of the Volhynian princes. Since the 14th century, it was the seat of the powerful Ostrogski princely family, who developed their town into a great center of learning and commerce. Upon the family's demise in the 17th century, Ostroh passed to the family of Zasławski and then Lubomirski.