"1648-57: Khmelnitsky: Crimea and Russia:" Khmelnitsky started his rebellion in alliance with the Khanate of Crimea. When his acceptance of Russian overlordship in 1654 (Treaty of Pereiaslav) led to the Russo-Polish War (1654–1667), the Crimeans switched sides and began raiding Ukraine. In his last years Khmelnitsky backed away from Russia and was negotiating with Sweden and Transylvania.