The Limfjord cuts across northern Denmark, offering a short and well-sheltered route from the North Sea to the Baltic. As maritime traffic picked up in the late 600s, ships began to ply the Limfjord more often. Traders coming from the commercial centers of the Frisian coast were taking their enterprise north, and by 705, they established a seasonal trading camp at Ribe in western Denmark. It gave them a final base before braving the North Sea into the Baltic. They carried beads with them wherever they went, and a few of their beads ended up in the young Limfjord settlement of Bejsebakken, indicating that they were using this route for their traffic by about 750.
In the mid-700s, the seasonal camps of southern Scandinavia had just started to transition into a more permanent network of trading towns. Ribe might have led the way, perhaps around 750. Åhus, Ribe’s sister site in southern Sweden, made a similar transition before 790. And the Limfjord was likewise affected, with a new settlement picking up at Sebbersund at about the same time.
What these three sites show us—Ribe, Sebbersund, Åhus—is that on the very cusp of viking raids on England, Ireland, and France, a stable network of settlements had just recently been formed in Scandinavia. These settlements offered a reliable route for shipping goods out of the North Sea and into the Baltic, and the Limfjord was the linchpin that held this network together.
But the sites of the Limfjord share a common problem with many sites from the Viking Age. Although we have a large number of artifacts that can tell us about the early and late periods of these places, there’s not much to fill in our knowledge of the middle decades of their existence.
The early phase ended sometime in the mid-800s, as the flow of glass beads into Sebbersund ground to a halt. A single coin minted by Louis the Pious between 822 and 840 was lost at the fledgling settlement of Aggersborg, indicating that the Limfjord was briefly but abortively linked into the coin economies of Western Europe. And the pagan cemetery at Lindholm Høje was first restructured and then subsequently abandoned after almost 500 years of continuous use. Local communities were reinventing who they were by redefining the ways they lived and died.
When archaeologists regain clarity in the mid-900s, the Limfjord region looked completely different. Sand dunes had covered the pagan burials at Lindholm Høje, and the residents of Sebbersund had begun to bury their dead alongside one of Scandinaiva’s earliest churches. The town of Aggersborg was burned to the ground, and on top of its ashes, the Danish king Harald Bluetooth had built a huge Trelleborg-style fortress.
Aggersborg dominated the maritime crossroads between England, Norway, and the Danish archipelago. Its walls stood 240 meters apart, enclosing 48 longhouses, each 32 meters in length. It was a remarkable sign of Danish royal power for anyone traveling through the Limfjord. Harald Bluetooth’s great-grandson Harthacnut installed a royal mint nearby at Aalborg. And one of his successors used the fort as a gathering point for his fleet—part of a failed attempt to invade England in 1085.
The Limfjord had evolved from a wayside for Frisian traders into the locus of Danish royal power and imperial ambitions. But sometime shortly before 1200, the shifting sands of the Jutland coast closed its access to the North Sea. This was no minor crisis. The Limfjord, once a proud commercial highway and the mustering place for armies, had turned suddenly into a brackish backwater. The suddenness of this change offers a grim reminder that even small environmental changes can rend a political and economic fabric that had been centuries in the making.