The Christianization of Kievan Rus', widely seen as the birth of the ROC, is believed to have occurred in 988 through the baptism of the Kievan prince Vladimir and his people by the clergy of the Ecumenical Patriarchate, whose constituent part the ROC remained for the next six centuries, while the Kievan see remained in the jurisdiction of the Ecumenical Patriarchate until 1686.
The ROC currently claims its exclusive jurisdiction over the Orthodox Christians, irrespective of their ethnic background, who reside in the former member republics of the Soviet Union, excluding Georgia and Armenia, although this claim is disputed in such countries as Estonia, Moldova and Ukraine and consequently parallel canonical Orthodox jurisdictions exist in those: the Estonian Apostolic Orthodox Church, the Metropolis of Bessarabia, and the Orthodox Church of Ukraine, respectively.
Her grandson, Vladimir of Kiev, made Rus' officially a Christian state.
The Christian community that developed into what is now known as the Russian Orthodox Church is traditionally said to have been founded by the Apostle Andrew, who is thought to have visited Scythia and Greek colonies along the northern coast of the Black Sea.
According to one of the legends, Andrew reached the future location of Kiev and foretold the foundation of a great Christian city.
There is evidence that the first Christian bishop was sent to Novgorod from Constantinople either by Patriarch Photius or Patriarch Ignatios, c. By the mid-10th century, there was already a Christian community among Kievan nobility, under the leadership of Bulgarian and Byzantine priests, although paganism remained the dominant religion.
Princess Olga of Kiev was the first ruler of Kievan Rus′ who became a Christian.
In December 1448, Jonas, a Russian bishop, was installed by the Council of Russian bishops in Moscow as Metropolitan of Kiev and All Russia (with permanent residence in Moscow) without the consent from Constantinople.