The years 1918–1921 were especially turbulent for "Kresy", due to the resurgence of the Polish nation-state and the formation of new borders. At that time, Poland had fought three wars to establish its eastern frontier: with Ukraine (see Polish–Ukrainian War), the Soviet Union (see Polish–Soviet War), and with Lithuania (see Polish–Lithuanian War). In all three conflicts Poland emerged victorious, and as a result, it recovered territories that had been previously annexed under Russian conquest and were east of the Curzon line, plus land formerly absorbed into Austrian Eastern Galicia. The region later formed the eastern provinces of the Second Polish Republic. Territories that were included in Kresy during the interbellum period comprised the eastern part of Lwów Voivodeship, Nowogródek Voivodeship, Polesie Voivodeship, Stanisławów Voivodeship, Tarnopol Voivodeship, Wilno Voivodeship, Wołyń Voivodeship, and the eastern part of Białystok Voivideship. The Polish government undertook an active policy of re-polonization in those territories (see Osadnik). This led to frequent conflicts with Ukrainian nationalists in the southeastern part of the "Kresy" region (see Pacification of Ukrainians in Eastern Galicia (1930)).