The territory, where this conflict broke out, was a part of the medieval Kievan Rus, and after the disintegration of this united Ruthenian state (in the middle of 12th century) belonged to the Ruthenian princedoms of Halych-Volhynia, Polotsk, Lutsk, Terebovlia, Turov-Pinsk etc. The majority of these principalities have been ruined during the Tatar-Mongol invasion in the middle of 13th century. Some territories in the Dniepr region and Black Sea Coast for long years lost Ruthenian settled population and became the so-called Wild Steppe (i.e., territory of the Pereyaslavl). After the Tatar-Mongol invasion these territories become an object of expansion of the Polish kingdom and the Lithuanian princedom. For example, in the first half of 14th century Kiev, the Dniepr region, also the region b