Book excerpt: For more than four thousand years, empires have been geographically the largest polities on Earth, shaping in many respects the human past and present in different epochs and on different continents. Covering the time span from the second millennium B.C.E. to the sixteenth century C.E., and geographic areas from China to South America, the case studies included in this volume demonstrate the necessity to combine perspectives from the longue duree and global comparativism with the theory of agency and an understanding of specific contexts for human actions. Contributions from leading scholars examine salient aspects of the Hittite, Assyrian, Ancient Egyptian, Achaemenid and Sasanian Iranian, Zhou to Han Dynasty Chinese, Inka, and Mughal empires.