Diego Olstein is Professor and Chair of the Department of History at the University of Pittsburgh, USA. He has published widely on medieval Spain, world history and historiography and taught or lectured on these subjects in North and Latin America, Europe, Israel, India, China, Korea, Japan, Singapore and Australia. Diego’s previous book, Thinking History Globally (Palgrave, 2015), defines, explains and exemplifies twelve transboundary branches of history, and his current interests revolve around globalization and hegemony in world history.