Treaty of Pereyaslav
The Treaty of Pereyaslav was concluded in 1654 in the Ukrainian city of Pereyaslav. The treaty provided for the protection of the Cossack state of Rus'-Ukraine (Ruthenia) by the Tsar of state of Muscovy (Moscow). The original copies of the treaty have perished, and the exact nature of the relationship stipulated by this treaty between Ukraine and Muscovy is a matter of scholarly controversy.In any event, the long-term consequences of the treaty included the separation of Ukraine from formerly dominant Catholic Poland, the strengthening of Orthodoxy in the historic center of Ukraine, and the eventual domination of Ukraine by neighboring Orthodox Russia. Ukraine's distinct identity soon became threatened by a process of Russification. For Poland, the treaty marked a beginning of sorts of a process of dismemberment leading to complete loss of independence. For the Tsars, the treaty led to the acquisition of Rus' proper, undergirding the transformation of their state from the regional Eurasian state of Muscovy to the European border state called "Rossiya," (Russia), and ultimately, the "Russian Empire."