As a result of territorial adjustments mandated by the Allies at the end of World War II in 1945, Poland's geographic centre of gravity shifted towards the west and the re-defined Polish lands largely lost their historic multi-ethnic character through the extermination, expulsion and migration of various ethnic groups during and after the war. By the late 1980s, the Polish reform movement Solidarity became crucial in bringing about a peaceful transition from a planned economy and a communist state to a capitalist economic system and a liberal parliamentary democracy. This process resulted in the creation of the modern Polish state, the Third Polish Republic, founded in 1989.