Nicola Di Cosmo is the Luce Foundation Professor in East Asian Studies at the Institute for Advanced Study in Princeton. His books include Ancient China and Its Enemies: The Rise of Nomadic Power in East Asian History. Lorenzo Pubblici is professor of premodern central Asian history and cultures at the University of Naples L’Orientale. His books include Mongol Caucasia: Invasions, Conquest, and Government of a Frontier Region in Thirteenth-Century Eurasia (1204–1295).