Hong Kong never became a communist society. It instead operates under a capitalist democratic government.
China was ruled by the so-called Communist Party after 1949, but it was not a Communist country. Communism means the abolition of the wages system and establishment of a classless society. China became state capitalist after 1949.
In 1989 Romania ended the communist period and became a capitalist democracy.
Germany, Italy, and America; these counties became unified during the 19th century.
Two separate states formed when Korea gained independence from Japan, with Communist North Korea and Capitalist South Korea
Communism means a classless stateless society based on production for use. Clearly no country became Communist after WW1, and Communism will have to exist at a global level anyway. Russia became state capitalist.
The economy was stagnated and the USSR collapsed. Gorbachev gave up communism, and Russia embraced "democracy".
Germany has had a primarily capitalist economy since the nation's unification in 1871 and the prior German confederations were also predominantly capitalist, in terms of the national economic policy. Under the Nazis, Germany became a corporatist state as opposed to a capitalist one. This non-capitalist nature continued in East Germany, which after World War II, became a Communist State and remained so until unification with West Germany in 1990. West Germany (and now Germany) has consistently been a capitalist state since its formation after World War II.
Kinda complicated. in 1910, before WW2, Japan invaded The Empire of Korea (no north or south at that time). They enslaved Koreans, and treated them horrible. after the USA bombed Japan in 1945, Japan pulled out. The northern part of Korea had a lot of Soviets and the south had the capitalist Americans. they fought and never concluded the war, so now, the north became Communist to please their northern Communist neighbors, and the south became capitalist to please us.
The United Kingdom has a parliamentary system.
Before WWI, Russia had been ruled by Tsars, similar to Kings. After WWI, Russia was a communist country known as the Soviet Union. It would be a communist country until 1990, when it became Russia again.
The Bolsheviks became the Communist Party in March 1918.