At the beginning of the seventeenth century nearly all of Ukraine was within the borders of Poland and the Polish King and the magnates were able to feel that Ukraine offered a purely Polish internal question. They were to be disillusioned. The formation of the Church Union and the Ukrainian cultural revival, together with the actions of the Kozak Host, proved that the Polish state as then constituted could not master the problem. The revolt of Khmelnitsky and his placing of the Host under the supremacy of the Tsar definitely established Ukraine as an international problem, perhaps the greatest in Eastern Europe. Poland had a last chance at the time of the Union of Hadiach in 1658, when it seemed for a moment as if Ukraine would enter along with Poland and Lithuania into a new tripartite form of government. It was not to be. The Kozaks were not willing to back Vyhovsky in his undertaking, the Polish King and magnates had learned nothing, and the scheme fell through. Instead there was made between the King and the Tsar the Treaty of Andrusivo in 1667 whereby Ukraine was definitely divided along the Dnyeper and Kiev passed into Muscovite hands. As we have seen, the struggle continued and Ukraine was cruelly devastated. More and more the Kozak Host was driven to the eastward and a large part of the Ukrainian lands in Poland lost contact with it. The last endeavor of the Kozaks came during the hetmanship of Mazepa, when Paly had endeavored to unite what was left of it in Poland with the main forces of the Kozaks. Poland was steadily falling into ruin. The Kings were no longer able to govern, except on paper, and during the eighteenth century, Russian and Swedish armies were constantly marching across her territory. The King and the magnates were only too ready to be peaceful, provided they were not asked to fight for themselves or for any else. It might have seemed an ideal time for a Kozak movement, but the main body of the Host had been so punished after the defeat of Mazepa, that it could give no support to the Kozaks in Poland. Step by step the Host vanished from the Polish lands. It was consistently deprived of its possible supports and from the early part of the eighteenth century, it ceased to play any role in Polish affairs.