The neighbours of the Russian people have increased in numbers as the Russian state has expanded from the original nucleus of the principality of Moscow, and as means of communication and weapons of war have caused the world to shrink until it can be said that most large states are neighbours of most others. The nature of the relations between the Russians and their neighbours was also profoundly affected by the Bolshevik Revolution, as a result of which Russia became not only a territorial Great Power but the centre of a world-wide revolutionary movement guided by the principles of Marxism–Leninism. Inevitably, at the three distinct levels of official foreign policy, of communist activity, and of contacts between peoples, Russia's relations with neighbouring countries have been more important than its relations with more distant lands. In the following brief survey an attempt has been made to strike a balance between these various factors.

THE RUSSIANS AND NEIGHBOUR NATIONS

The neighbours with whom the Russians have been for longest in contact in Europe are the Baltic peoples in the north-west, the White Russians in the west, the Ukrainians in the south-west, the Roumanians in the south, the Tatars in the south and south-east, and various Finno-Ugrian peoples in the north-east and in the Volga valley.

The origins and extent of the difference between Russians and Ukrainians are still the subject of controversy among historians. There is no doubt that the difference greatly increased after most of Russia came under Tatar, and most of the Ukraine under Lithuanian and Polish rule; but some would claim that great differences existed even before the Mongol invasion.