Mogren (2013: 81–3) emphasised the distinctly maritime character of these trading sites and the importance of an advanced nautical technology, enabling the transport of certain volumes of commodities. Interestingly, it seems increasingly apparent that the tentative introduction of the sail coincides with the establishment of seasonal trading sites (Mogren 2013; Zagal-Mach Wolfe 2013: 272–3; Kastholm 2014). Hence, a closer study of the anatomy of harbours is central to the discussion of urbanisation.

The harbour excavation of Hedeby from 1979/80 (Kalmring 2010a, 2011) up until today must be regarded as one of the very few examples of large-scale harbour surveys in Northern Europe. Its significance for the understanding of the strongly maritime Viking world, as well as its impact on the scientific community at the time, can be best compared to the significance of the recent excavations in the Theodosian harbour of Constantinople (Kocabaş 2012).