Short answers, pulled from the story.
The name Poland derives from the Polans, a West Slavic tribe that inhabited the Warta River basin between the sixth and eighth centuries. This word is rooted in the Proto-Slavic noun pole meaning field and reflects the flat topography of the region.
Poland officially became a state in 966 when the ruler of the Polans, Mieszko I, accepted Western Christianity under the auspices of the Roman Catholic Church. This act marked the beginning of statehood and was followed by the establishment of a missionary bishopric in Poznań in 968.
World War II began with the Nazi German invasion of Poland on the 1st of September 1939, followed by the Soviet invasion of Poland on the 17th of September. Poland lost the highest percentage of its citizens of all countries in the war, with around 6 million perishing, including 3 million Polish Jews and between 1.8 and 2.8 million ethnic Poles.
Poland became a full member of the European Union on the 1st of May 2004 following a referendum in June 2003. The country joined the Schengen Area in 2007, which dismantled borders with other member states and allowed for full freedom of movement within most of the European Union.
Poland has a population of approximately 38.2 million as of 2021, making it the ninth-most populous country in Europe. According to the 2021 census, ethnic Poles comprise 98.84 percent of the population, with 71.3 percent of all citizens adhering to the Catholic Church.