Oster starostwo at the end of XVI – at the beginning of XVII century

After the signing of the Union of Lublin, the territory of the Kiev Voivodeship and Oster starostwo went to the Polish–Lithuanian Commonwealth. In 1569 Oster, together with other cities of the Kiev voivodeship, swore allegiance to the king. Since this period, the population of the Oster region is growing rapidly, the number of osadniks is increasing. Thanks to the settlers, the population of Oster is growing, where in addition to the old city, a new one is being formed (now it is the modern Oster city). The newly built castle was located on the banks of the Desna River. In 1571 a garrison of 150 small nobles was stationed in Oster Castle. In the first half of the seventeenth century fortifications of Oster Starostwo center (Oster Castle) was reconstructed, the tower needed constant care. Constant construction and repairs required considerable funds. In 1626, the Oster starosta Jeremian Zaleski complained that there was no money to keep the castle due to small profits from Starostwo. The Lublin Union brought changes in the colonization process in the Starostwo territory. First of all, it enabled part of the petty nobility to obtain full noble status. On the territory of the Oster Starostwo sat the boyar families of Zhukinsky, Golovitsky, Dombrovsky, Skoda, Tolkach, Rubanky, Kurtsevichy, Sereda, Baransky (Baranovsky) etc. The Oster nobility received both individual and collective awards. The right to besiege the settlement was given to the new gentry, sometimes ancient boyar villages were bought, and sometimes captured. Through the efforts of the Oster starosta Mykhailo Ratomsky, such large settlements of the region as Bobrovytsia and Nosivka were besieged. Royal lustrations of Oster Starostwo in the first half of XVII century provide an opportunity to track changes in the existing land tenure structure. Kyiv monasteries have traditionally been large landowners in the Oster region