Human geopolitics, the competition for population rather than territory, is an essential but weakly understood dimension of world politics today. Such competition has preceded violent conflict throughout history, but has been muted since the Treaties of Westphalia laid the territorial foundations of the modern international system in the mid-seventeenth century. Today, however, human geopolitics is being resurrected in unanticipated ways, as governments are enabled and encouraged to engage their emigrant diasporas. How and why is this happening? Until now these questions have been difficult to answer. The majority of research attention has focused on questions of immigration policy in a handful of wealthy migrant destination countries, largely ignoring the emigration policies that preoccupy the world