Oster was founded in 1098 by Vladimir II Monomakh as Gorodets, a fortress belonging to the Pereiaslav principality, which was later inherited by his son Yuri Dolgorukiy.
The history of Oster began in 1098 when Vladimir II Monomakh established it as Gorodets, a fortified settlement within the Pereiaslav principality, which was later passed down to his son Yuri Dolgorukiy.