World history or global history as a field of historical study examines history from a global perspective. It emerged centuries ago; leading practitioners have included Voltaire (1694–1778), Hegel (1770–1831), Karl Marx (1818–1883), Oswald Spengler (1880–1936), and Arnold J. Toynbee (1889–1975). The field became much more active (in terms of university teaching, text books, scholarly journals, and academic associations) in the late 20th century. It is not to be confused with comparative history, which, like world history, deals with the history of multiple cultures and nations, but does not do so on a global scale. World history looks for common patterns that emerge across all cultures. World historians use a thematic approach, with two major focal points: integration (how processes of world history have drawn people of the world together) and difference (how patterns of world history reveal the diversity of the human experience). Establishment and perimeters of the field Jerry H. Bentley has observed that "the term world history has never been a clear signifier with a stable referent", and that usage of the term overlaps with universal history, comparative history, global history, big history, macro history, and transnational history, among others. The advent of world history as a distinct academic field of study can be traced to the 1960s, but the pace quickened in the 1980s. A key step was the creation of the World History Association and graduate programs at a handful of universities. Over the next decades scholarly publications, professional and academic organizations, and graduate programs in World History proliferated. World History has often displaced Western Civilization in the required curriculum of American high schools and universities, and is supported by new textbooks with a world history approach. World History attempts to recognize and address two structures that have profoundly shaped professional history-writing: A tendency to use current nation-states to set the boundaries and agendas of studies of the past. A deep legacy of Eurocentric assumptions (found especially, but not only, in Western history-writing). Thus World History tends to study networks, connections, and systems that cross traditional boundaries of historical study like linguistic, cultural, and national borders. World History is often concerned to explore social dynamics that have led to large-scale changes in human society, such as industrialization and the spread of capitalism, and to analyse how large-scale changes like these have affected different parts of the world. Like other branches of history-writing in the second half