Russian Empire
The Russian Empire, also known as Imperial Russia or simply Russia, was an empire that existed across Eurasia and North America from 1721, following the end of the Great Northern War, until the Republic was proclaimed by the Provisional Government that took power after the February Revolution of 1917.
History of the Eastern Orthodox Church
Russia lay under Mongol rule from the 13th through the 15th century. The Mongol invasion of Rus of 1237–1242AD lead to what is called the Tatar period in Russian history. This period lead to great calamity for the internal structure of Russia. Much of Russia was ruled by Mongols and Russian Princes (of whom had limited power).
The eventual end of the reign of the Golden Horde is said to have begun with the Battle of Kulikovo 8 September 1380. Which involves the famous Orthodox legend of Monk and Russian champion Alexander Peresvet and his death that mark the battle's beginning. The final pseudo-battle or face off that ended Mongol rule in Russia was the Great stand on the Ugra river in 1480AD. The death toll (by battle, massacre, flooding, and famine) of the Mongol wars of conquest is placed at about 40 million according to some sources.