Russia is a transcontinental country in Eastern Europe and North Asia. At 17,125,200 square kilometres (6,612,100 sq mi), Russia is the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, and the ninth most populous, with about 146.8 million people as of 2019, excluding Crimea. About 77% of the population live in the western, European part of the country.

The Czech Republic is a landlocked country located in Central Europe, but historically it has also been classified as an Eastern European country. The Czech Republic was known as the Kingdom of Bohemia in ancient times. It was the capital of the Holy Roman Empire and the birthplace of the Thirty Years Religious War. In modern times, it was the industrial center of the Austrian Empire and the Austro-Hungarian Empire. At the beginning of the 20th century, it became independent from Austria-Hungary due to the end of World War I and merged with Slovakia into Czechoslovakia. It was listed as one of the world's seven largest industrial countries. It was absorbed by Nazi Germany as a protectorate during World War II. During the Cold War era, the Soviet Union was pulled into the Eastern Bloc and became a satellite state of the Communist Party of the Soviet Union. In 1989, it broke away from the communist system and turned to democracy through the Velvet Revolution.

Hungary is one of the EU's medium-sized member states, and its capital and largest city is Budapest. In the 12th century, Hungary became one of the regional powers in Europe. In the 15th century, its culture and politics reached its peak. In the 19th century, it formed the Austro-Hungarian Empire with Austria and became one of the superpowers in Europe. After the First World War, the Austro-Hungarian Empire collapsed. After World War II, Hungary became a satellite country of the Soviet Union, and until 1989, Hungary became a parliamentary democracy.