January 8 (18), 1654 in the city of Pereyaslavl (now Pereyaslav-Khmelnytsky) hetman Bogdan Khmelnitsky convened the Rada - an assembly of representatives of the Ukrainian people - who decided on the reunification of Ukraine and Russia.
On the eve of the meeting B. Khmelnitsky met with the head of the tsar's embassy Boyar V. V. Buturlin. The Moscow embassy also included courtier I. Alferiev, clerk L. Lopukhin and representatives of the clergy. In the morning of 8 (18) January took place a meeting of Zaporizhye Cossacks’ Foremen Council, eventually called the General War Council. It was attended by representatives of the Cossack regiments and the inhabitants of Pereyaslavl, who, after the council voted unanimously for the unification of Ukraine and Russia. Later, in the middle of the day, an open Rada was convened - a great number of all ranks of people gathered". In addition to representatives of the regiments quartered in the territories, freed from the rule of the Polish-Lithuanian Commonwealth, the Rada was attended by the peasants of surrounding villages. Speaking at the meeting Khmelnitsky reminded of losses incurred by the Ukrainian and Belarusian peoples in the liberation struggle in 1648-1654 and stressed that the only way to consolidate the gains of the people is the recognition of the Russian rule. The proposal was met with unanimous approval, followed by the oath of allegiance to the tsar taken by Hetman Khmelnitsky, Cossack leaders, and then Cossacks and petty bourgeois.
The decision on reunification of the Ukraine and Russia was favored by the closeness of language and culture of the Ukrainian and Russian peoples, a common religion, along with economic, political and cultural relations established between the countries. An important role in this process also played particularities of the state system of Russia and the Russian government's policy towards Ukraine.
In Russia there were Cossack regions (near the Don River and Yaike River) free of serfdom which enjoyed some autonomy. Russian government provided shelter to Ukrainian peasants and Cossacks and housed them in its territory as free people. On the area adjacent to Ukraine there was formed a region of Ukrainian settlers and created a Cossack registry - Sloboda Ukraine. Ukrainian peasantry hoped to ensure their being free people under the Russian rule and get rid of national oppression and religious persecution. Cossack leaders and Ukrainian nobility sought the assistance of the Russian tsar to consolidate their class privileges and become the ruling class in the Ukraine by ensuring political autonomy within the Russian state.
On the whole, the reunification of Ukraine and Russia had progressive significance for further economic, political and cultural development of the Ukrainian people, it strengthened the alliance and friendship between the two brotherly peoples, who fought together against foreign invaders. Part of the Orthodox population of Poland, having joined the Russian state, got rid of the national and religious oppression. For Russia, the agreement resulted in the annexation of some lands in Western Russia.