The study of migration in the ancient world unexpectedly became a topic of the global news cycle in the summer of 2017. ‘The Story of Britain’, a BBC cartoon for schools that depicted a black soldier in Roman Britain generated Twitter exchanges, subsequently expanded into blogs, newspaper articles and think pieces around the world. Historians, archaeologists, geneticists, statisticians as well as others from outside academia contributed to a debate about the amount of ethnic diversity in Roman Britain and the origin and impact of ancient migrants to the British Isles. The editors of this volume do not expect that it will have an impact equivalent to the BBC cartoon, but we hope that the chapters within it can both contribute to the gradual disentanglement of scanty, sometimes contradictory, evidence and present new ways of looking at ancient migration, while also laying bare some of the tacit or unwarranted assumptions that have been made.