After World War Two, Europe was carved up by the Soviet Union and its former Western allies, and the Soviets gradually erected an "Iron Curtain" splitting the East from the West.

Defeated Germany was divided up by the occupying powers - the US, UK, France and the USSR - with the eastern part occupied by the Soviets. East Germany, officially known as the German Democratic Republic, became the Soviet Union's foothold in Western Europe.

But Berlin was split four ways, with British, French and American zones in the west of the city and a Soviet zone in the east. West Berlin became an island surrounded by communist East Germany.

The wall was eventually built in 1961 because East Berlin was haemorrhaging people to the West.

By the 1980s, the Soviet Union faced acute economic problems and major food shortages, and when a nuclear reactor at the Chernobyl power station in Ukraine exploded in April 1986, it was a symbolic moment in the impending collapse of the communist bloc.

Mikhail Gorbachev, the comparatively young Soviet leader who took power in 1985, introduced a reform policy of "glasnost" (openness) and "perestroika" (restructuring).

But events moved far faster than he could have foreseen.

Reform movements were already stirring in the communist bloc. Years of activism and strikes in Poland culminated in its ruling communist party voting to legalise the banned Solidarity trade union.

By February 1989, Solidarity was in talks with the government, and partially free elections in the summer saw it capture seats in parliament. Though the Communists retained a quota of seats, Solidarity swept the board wherever it was allowed to stand.

Hungarians, too, launched mass demonstrations for democracy in March. In May, 150 miles (240km) of barbed wire were dismantled along the border with Austria - the first chink in the Iron Curtain. Hungary's 1956 revolution was brutally suppressed by the Soviets, but this was succeeding.

By August, the revolutionary wave had truly re-ignited on the fringes. Two million people across Estonia, Latvia and Lithuania - then part of the Soviet Union - held one of the most memorable demonstrations of the so-called Singing Revolution when they formed a 370-mile (600km) human chain across the Baltic republics calling for independence.

In the heat of August, Hungary opened it borders to Austria in the west, allowing East German refugees an escape.

The Iron Curtain was buckling.

Czechoslovakia, whose push for liberalising reform had been brutally suppressed in 1968, provided another means of escape. East Germans could travel to the neighbouring socialist nation without restriction, and began to flood the West German embassy there by the hundreds, eventually being evacuated to the West by train. East Germany ended up closing its border with Czechoslovakia in October to stem the tide.

But by then the revolution had spread to East Germany itself. It began with demonstrators rallying for freedom in the centre of the city of Leipzig.

On 9 October, within days of East Germany celebrating its 40th anniversary, 70,000 people took to the streets.

There were calls for free elections from West Germany, and talk of reform from East Germany's new communist leader Egon Krenz. No-one knew the fall of the Wall was weeks away.

In late October parliament in Hungary, which had been among the first to hold mass demonstrations, adopted legislation providing for direct presidential elections and multi-party parliamentary elections.

And then on 31 October, the numbers demanding democracy in East Germany swelled to half a million. Mr Krenz flew to Moscow for meetings - he recently told the BBC that he had been assured German reunification was not on the agenda.

On 4 November, a month after the East German protests had begun, around half a million people gathered in Alexanderplatz in the heart of East Berlin.

Three days later, the government resigned. But there was no intention to give way to democracy and Egon Krenz remained head of the Communist Party and the country's de facto leader.

He would not be there long. Five days later, Mr Schabowski gave his world-changing press conference.

Earlier in '89, Beijing demonstrators in Tiananmen Square who had called for democracy in China were crushed in a major military crackdown.

The USSR had used its military to put down rebellions before. So why not now?

Within the Soviet Union itself, it did, killing 21 pro-independence protesters in the Soviet republic of Georgia. But elsewhere in the communist bloc, they did not.

In a break with Soviet policy, Mikhail Gorbachev decided against using the threat of military might to quell mass demonstrations and political revolution in neighbouring countries.

"We now have the Frank Sinatra doctrine," foreign ministry spokesman Gennady Gerasimov told US television. "He has a song, `I (Did) It My Way.' So every country decides on its own which road to take."

On 3 December, Mr Gorbachev and US President George HW Bush sat side by side in Malta, and released a statement saying the Cold War between the two powers was coming to a close. The 1989 wave of revolutions was not over yet.

Student demonstrators in Prague clashed with police, triggering the Velvet Revolution which overthrew Czechoslovak communism within weeks.

In Romania, demonstrations ended in violence and saw the fall of communist dictator Nicolae Ceausescu. A new government took over as the ousted leader fled his palace and angry crowds stormed it. He and his wife Elena were captured and executed on Christmas Day. More than 1,000 people were killed in unrest before and after the revolution, setting Romania apart from the largely bloodless events elsewhere.

And the Soviet Union itself?

In 1990, Latvia, Lithuania and Estonia took advantage of their new-found political freedoms to vote out their communist governments and make moves towards independence. The Soviet Union was falling apart, but Mr Gorbachev made one last ill-fated attempt to reform it by calling together the leaders of the 15 Soviet republics.

Hardline communists opposed to his reforms pre-empted him, attempting a coup while he was on holiday in Crimea in August 1991 and putting him under house arrest.

The coup was defeated in three days as pro-democracy forces rallied round Boris Yeltsin, president of the Russian republic.

But it was the death knell for the USSR, and one by one its constituent republics declared independence. By the end of the year the Soviet flag had flown for the last time.

Source: Fall of Berlin Wall: How 1989 reshaped the modern world - BBC News

The consequence of your mentioned event Chetna Chauhan was the economic globalization process, which has now come to a halt or even bifurcation.

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The market system is the basis of our civilization. Its only alternative is the Führer principle. Economic history is a long record of government policies that failed because they were designed with a bold disregard for the laws of economics. It is impossible to understand the history of economic thought if one does not pay attention to the fact that economics as such is a challenge to the conceit of those in power. The main achievement of economics is that it has provided a theory of peaceful human cooperation. This is why the harbingers of violent conflict have branded it as a dismal science and why this age of wars, civil wars, and destruction has no use for it.

Ludwig Von Mises (1990). “Economic freedom and interventionism: an anthology of articles and essays”.

Well, Chetna Chauhan, you simply have to dig in a bit ... for the necessary relevant information - if you couldn't find it on a summarized basis (for trading volume between eastern and western European countries, e.g., by decade) then you may look on a per country vs. block basis ... info like one seen next

" https://doi.org/10.1080/13507486.2019.1663796 "

in Table 1 on page 5: Distribution of Bulgaria’s imports and exports by blocs and some countries, 1960–1980.

... and, then, find similar info (for comparison purposes) for the time after 1990s.

Good luck

The fall of the Berlin Wall symbolically means the fall of the barriers between the socialist bloc and the Western countries, which expanded the trading opportunities.

The Cold War came to an end in 1989 with the fall of the Berlin Wall, which had a big effect on global trade. As a result, East and West Germany were reunited, and Eastern European nations were thereafter included in the international economy. This development made it easier to break down trade barriers between Eastern and Western Europe, expand trade opportunities, and open up new markets. Additionally, it cleared the path for trade liberalization, foreign investment, and the growth of international trade networks into formerly closed-off areas, all of which contributed to economic reforms in the former Eastern Bloc. All things considered, the down of the Berlin Wall aided in the expansion of interconnected markets and the globalization of trade.