The Principality of Novgorod-Seversk or Novhorod-Siversk was a medieval Rus' principality centered on the town now called Novhorod-Siverskyi. The principality emerged after the central power of Kievan Rus' declined in the late 11th century, and Sviatoslav Olgovich managed to establish a local dynasty, the Olgovichi, as a branch of the Rurikid house. Novgorod-Seversk was originally a subdivision of the Principality of Chernigov, and would go on to include territories that were earlier part of Chernigov and the Principality of Pereyaslavl.