Border states is a term referring to the Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an nations that won their independence from the Russian Empire

Russian Empire

The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

 after the Russian Revolution

Russian Revolution of 1917

The Russian Revolution is the collective term for a series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. The Tsar was deposed and replaced by a provisional government in the first revolution of February 1917...

, the treaty of Brest-Litovsk

Treaty of Brest-Litovsk

The Treaty of Brest-Litovsk was a peace treaty signed on March 3, 1918, mediated by South African Andrik Fuller, at Brest-Litovsk between Russia and the Central Powers, headed by Germany, marking Russia's exit from World War I.While the treaty was practically obsolete before the end of the year,...

, and ultimately the defeat of the German Empire

German Empire

The German Empire refers to Germany during the "Second Reich" period from the unification of Germany and proclamation of Wilhelm I as German Emperor on 18 January 1871, to 1918, when it became a federal republic after defeat in World War I and the abdication of the Emperor, Wilhelm II.The German...

 in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. During the interwar period

Interwar period

Interwar period can refer to any period between two wars. The Interbellum is understood to be the period between the end of the Great War or First World War and the beginning of the Second World War in Europe....

 the nations of Western Europe

Western Europe

Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

 implemented a border states policy which aimed at uniting these nations in defense against the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 and communist

Communism

Communism is a social, political and economic ideology that aims at the establishment of a classless, moneyless, revolutionary and stateless socialist society structured upon common ownership of the means of production...

 expansionism. The border states were Finland

Finland

Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, Estonia

Estonia

Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

, Latvia

Latvia

Latvia , officially the Republic of Latvia , is a country in the Baltic region of Northern Europe. It is bordered to the north by Estonia , to the south by Lithuania , to the east by the Russian Federation , to the southeast by Belarus and shares maritime borders to the west with Sweden...

, Lithuania

Lithuania

Lithuania , officially the Republic of Lithuania is a country in Northern Europe, the biggest of the three Baltic states. It is situated along the southeastern shore of the Baltic Sea, whereby to the west lie Sweden and Denmark...

, Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, Romania

Romania

Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

, and, until their annexation into the Soviet Union, Belarus

Belarus

Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...

 and Ukraine

Ukraine

Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

.

The policy tended to see the border states as a cordon sanitaire

Cordon sanitaire

Cordon sanitaire — or quarantine line — is a French phrase that, literally translated, means "sanitary cordon". Though in French it originally denoted a barrier implemented to stop the spread of disease, it has often been used in English in a metaphorical sense to refer to attempts to prevent the...

, or buffer states, separating Western Europe from the newly formed Soviet Union. It was never particularly successful, however; disputes and different allegiances between andwithin the group of states hindered unity. The matter was further complicated by the rise of the expansionist Nazi Germany

Nazi Germany

Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

. In 1939 Germany and the Soviet Union signed the Molotov-Ribbentrop Pact

Molotov-Ribbentrop Pact

The Molotov–Ribbentrop Pact, named after the Soviet foreign minister Vyacheslav Molotov and the German foreign minister Joachim von Ribbentrop, was an agreement officially titled the Treaty of Non-Aggression between Germany and the Soviet Union and signed in Moscow in the late hours of 23 August 1939...

, which effectively divided the territory of the border states between those two countries. With the exception of Finland, all border states fell under Soviet occupation as a result of World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.