Eastern Europe refers to the history of Ancient Rus or to the history of the ancient Mongols.

Eastern Europe belongs to the history of Ancient Rus. It was Ancient Russia from the period of the first Rurikovichs that was the largest state in Eastern Europe. In addition, such states as the Volga Bulgaria, Khazaria and partly the Golden Horde belonged to Eastern Europe.
Only the history of Mongolia and the neighboring regions of Russia and China is associated with the history of the ancient Mongols, the Mongols first reached Eastern Europe in the spring of 1223, they came to the Azov region from the Caspian Sea.