Lenin and his aides form the Soviet Union, by joining the Russian SFSR into a single state with the Byelorussian, Transcaucasian, and Ukrainian republics, on December 30, 1922.

Eventually internal border changes and annexations during the second World War will create a union of fifteen republics; the largest in size and population being the Russian SFSR, which will dominate the union for its entire history politically, culturally, and economically.

Under Stalin's leadership, the Soviet government launches a command economy, industrialization of the largely rural country, and collectivization of its agriculture.

During this period of rapid economic and social change, millions of people are sent to penal labor camps, including many political convicts for their suspected or real opposition to Stalin's rule; and millions are deported and exiled to remote areas of the Soviet Union.

The transitional disorganization of the country's agriculture, combined with the harsh state policies and a drought, lead to the Soviet famine of 1932–1933; which kills up to 8.7 million.

The Soviet Union, ultimately, makes the costly transformation from a largely agrarian economy to a major industrial powerhouse within a short span of time.

Some five million Red Army troops will be captured eventually by the Nazis; the latter deliberately starve to death or otherwise killed three point three million Soviet POWs, and a vast number of civilians, as the "Hunger Plan" seeks to fulfill Generalplan Ost.

Although the Wehrmacht has considerable early success, their attack is halted in the Battle of Moscow.

Subsequently, the Germans are dealt major defeats first at the Battle of Stalingrad in the winter of 1942–1943, and then in the Battle of Kursk in the summer of 1943.

Another German failure is the Siege of Leningrad, in which the city is fully blockaded on land between 1941 and 1944 by German and Finnish forces, and suffers tarvation and more than a million deaths, but never surrenders.

Soviet forces steamroll through Eastern and Central Europe in 1944–1945 and capture Berlin in May 1945.

In August 1945, the Red Army invades Manchuria and ousts the Japanese from Northeast Asia, contributing to the Allied victory over Japan. 

The Soviet Union enters the Second World War on September 17, 1939, with its invasion of Poland, in accordance with a secret protocol within the Molotov–Ribbentrop Pact with Nazi Germany.

The Soviet Union later invades Finland, and occupies and annexed the Baltic states, as well as parts of Romania.

On June 22, 1941, Germany invades the Soviet Union, opening the Eastern Front, the largest theater of the war.

East Europe (1984–1995 CE): Collapse of Communism and Post-Cold War Transitions

Political and Military Developments

End of Communist Rule

This era marked the dramatic collapse of communist regimes throughout Eastern Europe. The mid-to-late 1980s saw increased pressure from dissident movements, economic hardships, and changing geopolitical circumstances, notably influenced by Soviet leader Mikhail Gorbachev's policies of perestroika and glasnost.

Revolutions of 1989

The pivotal Revolutions of 1989 peacefully dismantled communist governments across the region, symbolized by the fall of the Berlin Wall. Nations such as Poland, Hungary, Czechoslovakia, East Germany, Bulgaria, and Romania transitioned to democratic governance, significantly altering regional political landscapes.

Dissolution of the Soviet Union

The political and economic reforms culminated in the dissolution of the Soviet Union in 1991, profoundly reshaping geopolitical alignments. Newly independent states emerged, notably Russia, Ukraine, Belarus, and the Baltic nations, dramatically transforming Eastern Europe's political structure.

Economic and Technological Developments

Transition to Market Economies

Eastern European countries underwent challenging transitions from centrally planned economies to market-driven systems. These transformations involved extensive economic restructuring, privatization efforts, and integration into global markets, accompanied by significant social and economic disruptions.

Technological Integration

Rapid integration of Western technologies occurred as Eastern Europe opened its economies to foreign investment and innovation. Technological modernization became crucial for economic recovery and competitive positioning within the global economy.

Cultural and Artistic Developments

Cultural Liberation and Diversification

The collapse of communism led to significant cultural liberalization, enabling diverse artistic expression and intellectual freedom. Cultural institutions flourished as censorship lifted, revitalizing literature, media, and the arts throughout the region.

Educational Reforms and Internationalization

Educational reforms focused on democratization, decentralization, and internationalization, significantly reshaping academic institutions. Higher education institutions increasingly collaborated internationally, fostering exchanges of knowledge and innovation.

Settlement Patterns and Urban Development

Urban Revitalization and Development

Urban areas underwent significant revitalization and redevelopment, addressing decades of infrastructural neglect. Investments focused on upgrading transportation networks, improving housing, and modernizing public services, transforming urban environments.

Strategic Reorientation

Military and strategic infrastructures realigned significantly, reflecting the new geopolitical realities. Border fortifications and military installations were reconfigured or dismantled as countries redefined their defense policies and security alliances.

Social and Religious Developments

Democratization and Social Change

Democratic reforms profoundly reshaped social structures, expanding political freedoms and civil liberties. Societies experienced rapid change and openness, addressing historical grievances and exploring new social models.

Revival of Religious Life

The post-communist era experienced a notable revival of religious expression and activity across Eastern Europe. Religious institutions regained autonomy and influence, playing active roles in societal rebuilding and reconciliation processes.

Long-Term Consequences and Historical Significance

The period from 1984 to 1995 CE was transformative, fundamentally reshaping Eastern Europe's political, economic, and social landscapes. The collapse of communism and transition toward democracy and market economies significantly altered regional dynamics and global geopolitics, setting a new course for Eastern Europe’s development in the post-Cold War era.

Economic and political turmoil begins to boil over in 1991 as the Baltic states choose to secede from the Soviet Union.

On March 17, a referendum is held, in which the vast majority of participating citizens vote in favor of changing the Soviet Union into a renewed federation.

In June 1991, Boris Yeltsin becomes the first directly elected president in Russian history when he is elected president of the Russian SFSR.

In August 1991, a coup d'état attempt by members of Gorbachev's government, directed against Gorbachev and aimed at preserving the Soviet Union, instead leads to the end of the Communist Party of the Soviet Union.

On December 25, 1991, following the dissolution of the Soviet Union, along with contemporary Russia, fourteen other post-Soviet states emerge.

The economic and political collapse of the Soviet Union leads Russia into a deep and prolonged depression.

During and after the disintegration of the Soviet Union, wide-ranging reforms including privatization and market and trade liberalization are undertaken, including radical changes along the lines of "shock therapy".

The privatization largely shifts control of enterprises from state agencies to individuals with inside connections in the government, which leads to the rise of the infamous Russian oligarchs.

Many of the newly rich move billions in cash and assets outside of the country in an enormous capital flight.

The depression of the economy leads to the collapse of social services—the birth rate plummets while the death rate skyrockets, and millions plunge into poverty; while extreme corruption, as well as criminal gangs and organized crime, rises significantly.