The countries of Europe are as diverse as they are prosperous. Of the top 15 countries in the Social Progress Index, 11 are in Europe. The people generally enjoy the benefits of democracy and free market economies and some of the highest standards of living in the world. Europe has a long history of conflict and war, and lay in ruins by the mid-20th century after two world wars. In rebuilding the devastated continent, the leaders tried to end the death and destruction once and for all by banding together. In 1993 the dream became a reality with the creation of the European Union, a political federation and common monetary zone. Still a work in progress, the European Union faces challenges in environmental issues, treatment of immigrants and minorities, unemployment, coordinating a common defense, and balancing between the wealthier nations of the north and the poorer countries of the south and former Soviet Union states.