The town’s position made it the western anchor of trade routes that ran south and east through Russian river systems toward Byzantium and the Abbasid Caliphate. Ships came in from both directions. Merchants settled. Craftspeople established workshops. At its height, Birka held an estimated 500 to 700 inhabitants — modest by the standards of later medieval cities, enormous by the standards of early medieval Scandinavia.
It had a fortification. Scholars refer to it as Borgen — a hill fort in the southern part of the island that provided both defensive capacity and a visible marker of the town’s organized social structure. Whether it functioned as what we would today call a garrison, housing a permanent military complement, is a matter of ongoing archaeological interpretation. What is clear is that the settlement was organized enough, valuable enough, and strategically positioned enough to require and support some kind of military infrastructure.
The town was also, for a place of its era, unusually well documented in its material remains. Around three thousand graves have been identified in the area — a figure that has made Birka one of the most intensively studied Viking Age burial sites in the world. Hjalmar Stolpe, a Swedish entomologist who originally came to Björkö to study amber, began excavating the graves in 1871 or 1872 and continued for approximately two decades. He documented his work with unusual care for the period — mapping grave positions, recording contents, labeling recovered materials. His records would prove crucial, more than a century after his death, to resolving questions that later scholars raised about his most famous find.