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 Byzantine Greek priests, although paganism remained the dominant religion.
Princess Olga of Kiev was the first ruler of Kievan Rus′ to convert to Christianity, either in 945 or 957.
Her grandson, Vladimir of Kiev, made Rus' officially a Christian state.
The official Christianization of Kievan Rus' is widely believed to have occurred in 988 AD, when Prince Vladimir was baptised himself and ordered his people to be baptised by the priests from the Eastern Roman Empire.
As Kiev was losing its political, cultural, and economical significance due to the Mongol invasion, Metropolitan Maximus moved to Vladimir in 1299; his successor, Metropolitan Peter moved the residence to Moscow in 1325.
Following the tribulations of the Mongol invasion, the Russian Church was pivotal in the survival and life of the Russian state.
It also exercises ecclesiastical jurisdiction over the autonomous Church of Japan and the Orthodox Christians resident in the People's Republic of China.
The Kievan church was a junior metropolitanate of the Patriarchate of Constantinople and the Ecumenical patriarch appointed the metropolitan, who usually was a Greek, who governed the Church of Rus'.
The Metropolitan's residence was originally located in Kiev itself, the capital of the medieval Rus' state.
Despite the politically motivated murders of Mikhail of Chernigov and Mikhail of Tver, the Mongols were generally tolerant and even granted tax exemption to the Church.
Such holy figures as Sergius of Radonezh and Metropolitan Alexis helped the country to withstand years of Tatar oppression, and to expand both economically and spiritually.
The ROC should not be confused with the Orthodox Church in America (OCA), another autocephalous Orthodox Church (since 1970, albeit not universally recognised in this status), that traces its existence in North America to the time of the Russian missionaries in Alaska (then part of the Russian Empire) in the late 18th century, and still adheres to the ROC liturgical tradition. The ROCOR was instituted in the 1920s by Russian communities outside then Communist Russia, which refused to recognize the authority of the Moscow Patriarchate then de facto headed by Metropolitan Sergius Stragorodsky.