A proud country with a history that dates back at least 1,100 years, Poland has outlived many of the powers that sought to absorb it. The Holy Roman Empire, Sweden, Prussia, Russia, and Austria all tried to expand at the expense of Poland. Though partitioning all but erased Poland from the map of Europe in the late 18th century, Napoleon created the Grand Duchy of Warsaw and later, the Congress of Vienna restored a Kingdom of Poland in 1815, with the Russian czar as monarch. From 1830 on, Poland became more and more Russified. This came to a halt with the rise of Josef Pilsudski's socialists who fought against the Russian Bolsheviks after World War I. By the terms of the Treaty of Riga in 1921, Poland was returned to borders approximating those of 1793 with a population about 70% ethnically Polish. There was also in Poland the largest population of Jews in Europe, at this point. In 1939, Germany attacked Poland along with the Soviet Union. Divided between the two then-allies, Poland suffered great losses during the war,including the destruction of nearly its entire population of 3,000,000 Jews to the Nazi concentration camps erected all over Poland. A Polish government-in-exile was established in London but its effectiveness was limited. The Soviets took control of Poland as the war drew to a close, and recognizing a provisional government based in Lublin. The Allies met in Yalta in 1945 and there were convinced by the USSR to allow the eastern part of Poland to be absorbed into the Soviet Union and that some of eastern germany should be incorporated into Poland, giving Poland roughly the borders of its 10th century incarnation. By 1949, the communist party was in control of Poland. Under communist rule, Poles lived under tight control. Party Chairman Gomulka was briefly thought to be committed to pursuing a measure of intellectual and cultural freedom for his people, but this was short-lived. Growing national discontent and the election of a Polish cardinal, Karol Wojtyla, as Pope John Paul II, jump-started the forces of nationalism and reform until in 1990 the communist party voted to dissolve. Solidarity, a national labor union, became a uniting force for the country and its charismatic leader Lech Walesa, actually became president. Poland is becoming a strong economic force in eastern Europe, with much foreign investment and a healthy GDP. In 1999, Poland joined NATO, the ultimate step in ensuring Poland's protection from any Russian plans to reestablish domination over the area.