Ros region [Поросся; Porossia]. A historical-geographic region located between the Ros River and the Stuhna River south of Kyiv (today the southern part of Kyiv oblast and northern tip of Cherkasy oblast). Ros was settled originally by the Polianians, and developed into a frontier area of the Kyivan Rus’ empire. A number of fortified towns were established there in the 10th century, among them Bohuslav, Korsun, Kaniv, and Yuriv (later Bila Tserkva). War captives, among them many Poles, were settled in the region to provide a frontline force against attacks by steppe nomads. In the 12th century, Pechenegs and Torks began settling in the region and mixing with the local population. The area was overrun by the Tatars in the 13th century, and its fortresses sacked. All references to Ros as a distinctive region then ceased.
[This article originally appeared in the Encyclopedia of Ukraine, vol. 4 (1993).]