The concept of the Western part of the earth has its roots in Greco-Roman civilization in Europe, and the advent of Christianity. In the modern era, Western culture has been heavily influenced by the traditions of the Renaissance, Protestant Reformation, Age of Enlightenment—and shaped by the expansive colonialism of the 15th-20th centuries. Before the Cold War era, the traditional Western viewpoint identified Western Civilization with the Western Christian (Catholic-Protestant) countries and culture. Its political usage was temporarily changed by the antagonism during the Cold War in the mid-to-late 20th Century (1947–1991).