The expansion of the by now fully organized, respected and extremely powerful Russian Orthodox Church really began in the late 17th and 18th centuries respectively.
Local political leaders were convinced that if they converted to orthodoxy that they would be amply rewarded with financial as well as political gains if they would bring their followers with them. They were also offered the chance to escape military service for this conversion which led to the widespread conversion of many among them including their followers.
The next two centuries saw countless missionary expeditions into the Siberian regions and well into Alaska as well. The missionaries in their zeal to convert the local learned the languages and had the gospels and hymns of the religion translated in order to spread the word of Christianity as a whole, and Russian Orthodoxy in particular to the inhabitants of those lands.
After the Treaty of Pereyaslav, the Metropolis of Kiev was transferred from the jurisdiction of Constantinople to Moscow. The result was the heavy and controversial transfer of millions of followers into the patriarch of Moscow and the domination of the Ukrainians which lasted well into the 18th century.
The Church continued to flourish and the rapid expansion continued along these lines for many decades. There was a period of modernization in this era as well. In the later part of the 18th century, there was mass spiritual revival that became very significant and in which some of the key concepts of the newly renovated Orthodox doctrine was established and communicated to the masses.
This revival and resurgence of Eastern Orthodoxy was heavily reflected in much of the Russian literature around this time, and gave one a great understanding of the power and influence the Church had over its many followers at that time in history.
This period of relative calm and easy existence would soon be tested by the Russian revolution and the emergence of a new and unknown threat that was to become communism.