Ancient Greece and ancient Rome are generally considered to be the birthplaces of Western civilization, the former due to its impact on Western philosophy, democracy, science, and art, the latter due to its influence in governance, republicanism, law, architecture and warfare. The West is also founded upon Christianity, particularly Roman Catholicism and various Protestant churches, which is in turn founded upon Hellenism, Roman culture and Judaism; the Ancient Greeks and Hebrews in turn took and "reused" forms from the civilizations of the ancient Near East. The concept of the Western part of the earth has its roots in the theological, methodological, and emphatical division between the Western Roman Catholic and Eastern Orthodox Churches. 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 imperialism and colonialism of the 15th to 20th centuries.
West was originally literal, opposing Catholic Europe with the cultures and civilizations of the Middle East and North Africa, Sub-Saharan Africa, South Asia, Southeast Asia, and the remote Far East which early-modern Europeans saw as the East. Western world sometimes refers to Europe and to areas whose populations largely consist of ethnic Europeans spread through the Age of Discovery's Christian imperialism.
Western culture was influenced by many older great civilizations of the ancient Near East, such as Phoenicia, Ancient Israel, Minoan Crete, Sumer, Babylonia, and also Ancient Egypt. It originated in the Mediterranean basin and its vicinity; Greece and Rome are often cited as its originators. Over time, their associated empires grew first to the east and west to include the rest of Mediterranean and Black Sea coastal areas, conquering and absorbing. Later, they expanded to the north of the Mediterranean Sea to include Western, Central, and Southeastern Europe. Christianization of Ireland (5th century), Christianization of Bulgaria (9th century), Christianization of Kievan Rus' (Russia, Ukraine, Belarus; 10th century), Christianisation of Scandinavia (Denmark, Norway, Sweden; 12th century) and Christianization of Lithuania (14th century) brought the rest of present-day European territory into Western civilisation.
Historians, such as Carroll Quigley in The Evolution of Civilizations, contend that Western civilization was born around 500 AD, after the total collapse of the Western Roman Empire, leaving a vacuum for new ideas to flourish that were impossible in Classical societies. In either view, between the fall of the Western Roman Empire and the Renaissance, the West (or those regions that would later become the heartland of the culturally "western sphere") experienced a period of first, considerable decline, and then readaptation, reorientation and considerable renewed material, technological and political development. This whole period of roughly a millennium is known as the Middle Ages, its early part forming the "Dark Ages", designations that were created during the Renaissance and reflect the perspective on history, and the self-image, of the latter period.
The knowledge of the ancient Western world was partly preserved during this period due to the survival of the Eastern Roman Empire and the institutions of the Catholic Church; it was also greatly expanded by the Arab importation of both the Ancient Greco-Roman and new technology through the Arabs from India and China to Europe. Since the Renaissance, the West evolved beyond the influence of the ancient Greeks and Romans and the Islamic world due to the Commercial, Scientific, and Industrial Revolutions, and the expansion of the peoples of Western and Central European empires, and particularly the globe-spanning empires of the 18th and 19th centuries. Numerous times, this expansion was accompanied by Christian missionaries, who attempted to proselytize Christianity.