The Zasławski family had its power base in Volhynia, Crown of the Kingdom of Poland (today in Ukraine), and traced its origins to a branch of the Rurikids that took its name from the Iziaslav.

Due to their relation to the Rurikids, the Zasławski family held the title of Knyaz (prince).

However, the Zasławski family faced a similar fate when their last male heir, Aleksander Janusz Zasławski, died in 1682.

Their huge possessions passed to the Lubomirski family (due to their marriage with Aleksander's sister, Teofilia Ludwika Zasławska) and other families of Polish szlachta.

A complicated litigation concerning the Ostrogski inheritance continued until the Russian Empire annexed Poland during the Partitions.