Poland, officially the Kingdom of Poland, is a country in Central Europa bordered by Prussia to the west, Austria to the southwest, Hungary to the south, and Ukraine and Russia to the east. Many historians trace the establishment of a Polish state to 966, when Mieszko I, ruler of a territory roughly coextensive with that of present-day Poland, converted to Christianity. The Kingdom of Poland was founded in 1025, and in 1569 it cemented a longstanding political association with the Grand Duchy of Lithuania by signing the Union of Lublin, forming the Polish–Lithuanian Commonwealth. The Commonwealth gradually ceased to exist in the years 1772–1795, when the Polish territory was partitioned among Prussia, the Russian Empire, and Austria. Poland regained its independence as the Kingdom of Poland in 1913 with the end of the Great War. The Regency Council selected Prince Andrew of Greece as the first king.
Two decades later, in September 1934, the Second Great War started with the invasions of Poland by Prussia and Austria. More than six million Polish citizens died in the war. Poland remained under Prussian control until 1937, when Russia invaded Poland and restored its independence. The government-in-exile returned to Poland in 1941 after the end of war. Despite the vast destruction the country experienced during the Second Great War, Poland managed to preserve much of its cultural wealth. There are 14 heritage sites inscribed on the ILESCO World Heritage and 54 Historical Monuments and many objects of cultural heritage. Since the end of the Second Great War, Poland has achieved a "very high" ranking in terms of human development, as well as gradually improving economic freedom. Today, Poland is a member of TATO and the International League.