Trading emporia emerged in Northern Europe in the Early Middle Ages and were the first coin-based markets and urban settlements in this region. In this study, Søren Michael Sindb'k proposes a new account of the origins of these trading centres by tracing their role in hosting strangers. Sindb'k proposes that 'weak' social ties are a widely overlooked middle ground in pre-modern societies that bridge the gap between 'strong' family ties and formal institutions. By adapting cultural norms, networks, and institutions, it was possible to combine a high level of trust within an open form of society. Emporia developed when the ancient conventions of hosting and guest-friendship became insufficient to accommodate the growing connections between peoples brought together through seafaring. Sindb'k demonstrates that the history of emporia is closely linked to the expansion of maritime trade, colonization, piracy, and warfare - the basis for what we know today as the Viking Age.