# Diego Olstein

Diego Olstein (also known as Diego Holstein, born 24 March 1970) is a professor of history and department chair at the University of Pittsburgh. He was associate and interim director of the World History Center (2011–2017) and a member of the executive boards of the European Network of Universal and Global History (2005-2011) and the World History Association (2016-2018).

## Biography

Diego Olstein, grandson of Jewish immigrants from Poland and Russia, was born and raised in Bahía Blanca, Argentina. Upon graduation from Colegio Nacional and Seminario Dr. Hertzl high schools, he migrated to Israel. He earned a BA in history and psychology at the Hebrew University of Jerusalem, where he continued to graduate studies. He wrote his MA thesis (1995-1996) and PhD dissertation (1998-2003) on medieval Spanish history under the supervision of Benjamin Ze’ev Kedar. During these formative years he worked in close collaboration with Moshe Zimmerman and Nathan Sussman at the Hebrew University, and Reyna Pastor, Ana Rodriguez López, and Eduardo Manzano while residing at the Universidad Complutense and Centro de Investigaciones Científicas (CSIC) in Madrid, and with Thomas Glick at Boston University.
In 2004, Olstein returned to Israel and joined the faculty of the Hebrew University as a member of the Department of History until 2011. In 2009-2010 he was a visiting professor at the University of Wisconsin, Madison, and in 2011 he was appointed Associate Professor at the Department of History at the University of Pittsburgh, where he also became Associate Director of the World History Center. In 2017, he was appointed Full Professor.
Olstein is married to Irit Lerner-Olstein. They are the parents of Racheli, Ariel, and Maya.

## Research
### Medieval Spanish history

Olstein’s work on Medieval Spanish history concentrates on the processes of conquest and settlement, cultural diffusion, acculturation, and assimilation that unfolded during the twelve and thirteenth centuries in the city of Toledo and its rural area in the wake of the Castilian conquest (1085). He focused on the patterns of interaction between the two largest groups in both city and hinterland: the Christian settlers from the north and the local Mozarabs, i.e. Arabized Christians. In his book La Era Mozárabe, Olstein asserts that after a century of self-imposed segregation, by the 1180s a process of intermingling between these two societies started evolving, reflected in the gradual demographic homogenization of the landscape, the growth of economic and neighboring relationships between communities, and the increasing rate of inter-community marriages. As a result of that, the Arabized Christians progressively adopted the Romance language (medieval Spanish) at the expense of their Arab language, redefined their identity, and became assimilated into the new settler society during the 14th century. However, amidst its own assimilation, the Mozarab community was able to acculturate the northern Christians by providing them with part of their Arab and Muslim economic, legal, and notarial legacies.

### Historiographical analysis

Side by side with his research on Medieval Spanish history and particularly the Mozarab minority, Olstein paid attention to the history of historical writing on these topics contextualizing them in the changing socio-economic, intellectual, ideological, and political conditions throughout the nineteenth and twentieth centuries in Spain. Subsequently, his historiographical interests gravitated towards the varieties of macro-historical approaches - such as the world-system, historical sociology, and world history - that study the past on larger scales of space and time. In Thinking History Globally, Olstein outlines the research methods, agendas, and professional networks of twelve distinctive historical branches that frame their analysis of the past beyond closed boundaries: comparative, relational, international, transnational, oceanic, global, world, and big histories, history of globalization, historical sociology, world-system approach, and civilizational analysis. Beyond their singularities, the book arranges these twelve branches under the four big C’s for thinking history globally: comparisons, connections, conceptualizations, and contextualizations.

### Global and world history

The conceptualization of the macro-historical approaches was followed by publications on world history. In “‘Proto-globalization’ and ‘Proto-glocalizations’ in the Middle Millennium” (Cambridge World History. Volume 5: Expanding Webs of Exchange and Conquest, 500-1500 CE), Olstein mapped the connections throughout the Eastern and Western hemispheres concluding that the Middle Millennium (a more ecumenical concept than the European Middle Ages for referring to the period 500-1500 CE) was made of a multiplicity of tiny local worlds, in which, nevertheless, regional and even hemispheric forces such as conquest, trade, and religious conversion had had defining impacts on local societies. In other publications on world history, Olstein moved beyond his expertise in medieval studies outlining broader arguments, for example, by periodizing world history according with three major regional divergences: the “Greatest divergence” starting by the end of the last Ice Age (ca. 15,000 before the present) and isolating the Old and the New Worlds from one another till ca. 1500; the “Great divergence” bifurcating the paths of Europe and Afro-Asia since ca. 1500; and the “American divergence” that divided the fortunes of the New World societies from ca. 1500 onwards. Similarly, he periodized the history of globalization into six distinctive phases: Three waves of “hemispherization” in Afro-Eurasia during the age of Classical, Muslim, and Mongol Empires and three waves of globalization during the ages of colonialism, industrialization, and neoliberalism.
Olstein’s last book A Brief History of Now presents a global history of the last two centuries analyzing the interplay between technological innovation, economic globalization, hegemonic world order, political regimes, and socio-economic inequality.