Valerie Hansen received her Ph.D. from the University of Pennsylvania in 1987. She is Professor of History at Yale University, where she teaches courses in East Asian history, especially pre-modern China. Her many scholarly publications include CHANGING GODS IN MEDIEVAL CHINA, 1127?1276 (Princeton UP, 1990) and NEGOTIATING DAILY LIFE IN TRADITIONAL CHINA: HOW ORDINARY PEOPLE USED CONTRACTS, 600-1400 (Yale UP, 1995). She is also author of THE OPEN EMPIRE: A HISTORY OF CHINA TO 1600 (WW Norton, 2000) and THE SILK ROAD: A NEW HISTORY (Oxford UP, 2012). As co-author of the Cengage Learning text VO...