Human migration is as old as history and as current as today’s headlines of law enforcement operations and tragedy. Amid the encounters, the question remains: how do strangers become a single people? Today, more than 90 per cent of China’s population identifies as Han Chinese, despite centuries of migration and upheaval. Historians once credited this unity to strong rulers, uniform writing and Confucius. But archaeologists in China are finding the answer in the bowl rather than the sword or pen....