Comparative history
Comparative history is the comparison of different societies which existed during the same time period or shared similar cultural conditions. The comparative history of societies emerged as an important specialty among intellectuals in the Enlightenment in the 18th century, as typified by Montesquieu, Voltaire, Adam Smith, and others. Sociologists and economists in the 19th century often explored comparative history, as exemplified by Alexis de Tocqueville, Karl Marx, and Max Weber. In the first half of the 20th century, a large reading public followed the comparative histories of (German) Oswald Spengler, (Russian-American) Pitirim Sorokin, and (British) Arnold J.  Toynbee. Since the 1950s, however, comparative history has faded from the public view, and is now the domain of specialized scholars working independently. Besides the people mentioned above, recent exemplars of comparative history include American historians Herbert E. Bolton and Carroll Quigley, and British historian Geoffrey Barraclough. Several sociologists are also prominent in this field, including Barrington Moore, S. N. Eisenstadt, Seymour Martin Lipset, Charles Tilly, Stephen O. Murray, and Michael Mann. Historians generally accept the comparison of particular institutions (banking, women's rights, ethnic identities) in different societies, but since the hostile reaction to Toynbee in the 1950s, generally  do not pay much attention to sweeping comparative studies that cover wide swaths of the world over many centuries. Notable topics. Comparative studies of the Roman and Han empires. The ancient Chinese and Roman Empires are often compared due to their synchronous and analogous developments from warring states into universal empires. Atlantic history. Atlantic history studies the Atlantic World in the early modern period. It is premised on the idea that, following the rise of sustained European contact with the New World in the 16th century, the continents that bordered the Atlantic Ocean—the Americas, Europe, and Africa—constituted a  regional system or common sphere of economic and cultural exchange that can be studied as a totality. Its theme is the complex interaction between Europe (especially Britain and France) and the New World colonies. It encompasses a wide range of demographic, social, economic, political, legal, military, intellectual and religious topics treated in comparative fashion by looking at both sides of the Atlantic. Religious revivals characterized Britain and Germany, as well as the First Great Awakening in the American colonies. Migration and race/slavery have been important topics. Although a relatively new field, it has stimulated numerous studies of comparative history  especially regarding ideas, colonialism, slavery, economic history, and political revolutions in the 18th century in North and South America, Europe and Africa. Modernization models. Beginning with German and French sociologists of the late 19th century, modernization models have been developed to show the sequence of transitions from traditional to modern societies, and indeed to postmodern societies. This research flourished especially in the 1960s, with Princeton University setting up seminars that compared the modernization process in China, Japan, Russia and other nations. Modernization theory and history have been explicitly used as guides for countries eager to develop rapidly, such as China . Indeed, modernization has been proposed as the most useful framework for world history in China, because as one of the developing countries that started late, "China's modernization has to be based on the experiences and lessons of other countries." Comparative politics. The field of comparative history often overlaps with the subdivision of political science known as comparative politics. This includes "transnational" history and sometimes also international history. Comparative history of minorities. Mordechai Zaken compared two non-Muslim minorities in Kurdistan, the Jews and the Assyrian Christians in their relationships with their Muslim rulers and tribal chieftains during the 19th  and 20th centuries. His comparative study gave a much clearer picture on the status of the minorities and their relationships with the ruling elites in and around Kurdistan. His PhD dissertation and the book upon which it was based have been widely spread and translated into the local languages in Kurdistan and the surrounding. Military history. Military historians have often compared the organization, tactical and strategic ideas, leadership, and national support of the militaries of different nations. Historians have emphasized the need to stretch beyond battles and generals to do more comparative analysis. Slavery. The study of slavery in comparative  perspective, ranging from the ancient world to the 19th century, has attracted numerous historians since the 1960s. Economics. Much of economic history in recent years has been done by model-building economists who show occasional interest in comparative data analysis. Considerable work has been done by historians on the "Great Divergence" debate launched by Kenneth Pomeranz in 2009. At issue is why Europe moved forward rapidly after 1700 while Asia did not. More traditional research methodologies have been combined with econometrics, for example in the comparison of merchant guilds in Europe. Quantitative methods. Since the work of Sorokin, scholars in  comparative history, especially if sociologists and political scientists, have often used quantitative and statistical data to compare multiple societies on multiple dimensions. There have been some efforts made to build mathematical dynamic models, but these have not come into the mainstream comparative history.