Birka and Hovgården

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Birka and Hovgården are two sites in Sweden that together form an archaeological complex dating from the Viking Age, inscribed on the UNESCO World Heritage List. The sites are located on the islands of Björkö and Adelsö, respectively, in Lake Mälaren, approximately 30 kilometres west of Stockholm. Birka was founded in the mid-8th century. At that time, Lake Mälar formed a bay of the Baltic Sea, with sea levels approximately five meters higher than today. Birka occupied a strategic position, sheltered by a network of islands and skerries and located at the intersection of several major maritime routes. It developed into a principal center of trade in Sweden, surpassing the older site of Helgö and expanding on a significantly larger scale, with an estimated peak population of 700 to 1,000 inhabitants. The settlement concentrated a wide range of craft activities that relied on raw materials sourced from Scandinavian regions, including amber, iron from Bergslagen, furs and down, antler, and ivory. Manufactured goods were distributed locally to surrounding farms and, more extensively, exported in exchange for luxury items such as pottery, silk and fine embroidery, and silver. Trade initially...

The name Birka represents the Swedish form of the Latin name Birca, which appears in contemporary sources such as the Vita Anskarii by Rimbert. The origin of the name is debated. One view is that it is a Latinization of Björkö, meaning “island ( ö ) of birches ( björk ).” From the Middle Ages onward, the term Birk was used to designate various Scandinavian locations, particularly trading towns with a special legal status under the laws of Bjarkey. It is therefore possible that the name of the trading town described by Rimbert derives from this concept. Some scholars propose the reverse possibility, suggesting that the name Birk or Bjarkey originated from Birka/Björkö, which may have been the first settlement to possess such a status, and that other trading towns later adopted similar laws, retaining the designation “laws of Bjarkey.”

The identification of Birka with the site of Björkö has been the subject of historical debate since the 18th century. Alternative locations have been proposed, including sites in Västergötland, Östergötland, and the Åland Islands. Contemporary analysis of written sources, together with extensive archaeological evidence, has established a scholarly consensus that the Birka described by Rimbert corresponds to the settlement on Björkö during the Viking Age.

The name Hovgård or Hovedgård was a common term in medieval Sweden, referring to an estate belonging to a person of high rank or to the principal estate of a large landholding. The name of the island Adelsö literally means “island of the nobility.”

Birka and Hovgården are located on the islands of Björkö and Adelsö, respectively, in Lake Mälar, approximately 30 km west of Stockholm. Both islands are part of the Ekerö Municipality within Stockholm County. The islands face each other and are separated by a strait a few hundred meters wide. According to its designation as a World Heritage Site, the protected area covers 226 hectares, including the entire northern part of Björkö and the Hovgården site. A buffer zone of 2,272 hectares surrounds this area, encompassing the remainder of Björkö, a large portion of Adelsö, and part of the lake between the two islands.

Lake Mälar is geologically part of the sub- Cambrian peneplain. The region is characterized by numerous faults and fissures, resulting in a rugged landscape and a high density of islands. At the end of the Quaternary glaciations, glaciers exposed bedrock and deposited moraines, while the area that now forms Lake Mälar was submerged. Sediments, particularly clay, accumulated in the deepest parts. Post-glacial rebound gradually raised the land, leading to the emergence of these areas. On Björkö and Adelsö, this process created rocky plateaus, which are generally infertile and forested, alongside clay plains, which rank among the most fertile in Sweden after Scania.

Isostatic rebound continues at an average rate of approximately 0.5 cm per year. During the Viking Age, water levels were around five meters higher than present, and the area of the modern lake was then part of the Baltic Sea. At that time, the current island of Björkö was divided into two sections, with the northern part called Björkö and the southern part called Grönsö, while Hovgården occupied the southern tip of Adelsö.

The earliest evidence of human activity in the area is a cemetery northwest of Hovgården, which appears to have been in use between approximately 600 and 1100. On Grönsö, which was a separate island during this period, Bronze Age cairns have also been identified. The proto-city of Birka and the adjacent royal estate of Hovgården were established in the 8th century. The precise founding date is uncertain but is generally estimated around 750. The style of the earliest artifacts at the site corresponds to the transitional period between the Vendel Age and the Viking Age, at the very end of the 8th century. These artifacts show similarities to objects found at Staraya Ladoga, which was founded around 753 according to dendrochronological analysis. The oldest building at Birka, located near the defensive wall, has been dated to the mid-8th century.

During this period, most of Sweden had an agrarian economy, with inhabitants living on largely self-sufficient farms that combined agriculture, forest resource use, hunting, and fishing. The Viking Age saw the development of proto-urban settlements where trade and craft activities were concentrated, both in Sweden and in other regions around the Baltic Sea, with examples including Hedeby, Ribe, and Staraya Ladoga. In Sweden, a similar site existed to some degree during the Vendel period, namely Helgö, located on an island about 10 km southeast of Birka. Helgö was active approximately between 200 and 800 and is considered a predecessor of Birka, although its scale and significance were likely smaller. The site was probably linked to a royal residence at Hundhamra [ fr ], located on a neighboring island, a pattern that was later repeated with Birka and the royal estate of Hovgården.

The island of Björkö was a favorable location for trade. It is situated on what is now Lake Mälar, which during the Viking Age was an extension of the Baltic Sea and formed the central region of Svealand, serving as a principal route of communication at a time when few developed land routes existed. The island occupies a strategic position at the intersection of several key lake routes: to the south, the Södertälje passage (later closed due to post-glacial rebound and redeveloped in the 19th century with the Södertälje Canal ); to the north, the Fyrisleden route toward Gamla Uppsala ; to the west, inland regions including access to the metal resources of Bergslagen ; and to the east, the passage near present-day Stockholm. Additionally, the network of islands and channels formed by the Mälaren and Stockholm archipelagos provided a significant degree of natural protection for the island’s inhabitants.

In contrast to the agrarian economy prevalent in most of Sweden, Birka functioned primarily as a center for trade and craft production.

The city’s commercial activity can be divided into two main phases. The first phase, from the city’s foundation until the end of the 9th century, was characterized by predominantly Western European trade, particularly with the trading towns of Dorestad and Wolin. The second phase involved increased trade with eastern regions, including present-day Russia and parts of the eastern Muslim world. This development was associated with the establishment of Kievan Rus’ by Swedish settlers ( Varangians ) and the opening of trade routes along the Volga trade route and Dnieper trade route. During this period, Birka experienced growth, reaching an estimated peak population of 700 to 1,000 inhabitants.

The main export commodities from Birka included iron from Bergslagen, furs from locally hunted animals or obtained from Sami and Finnic peoples, reindeer or elk antlers, walrus ivory, amber, honey from southern Sweden, and eiderdown. Slaves were also exported to eastern markets. Many of these goods were likely transported from northern Scandinavia to Birka during winter, when snow and ice facilitated overland movement of heavy items. It is also possible that large markets were held on the frozen Baltic Sea near Birka during winter, a practice documented in the Middle Ages.

In Birka, many exported goods were processed locally before being sold. Animal antlers were carved into combs, iron was forged into tools and other items, and furs and leather were tanned. The town also produced textiles and jewelry. Not all craft production was intended for long-distance trade; a significant portion supplied farms in the surrounding region. This local distribution was necessary because Birka was not self-sufficient, and its population relied on regional farms for food, fuel, and building materials. Estimates suggest that, given the limited agricultural surplus, up to one-quarter of the Mälardalen may have been required to sustain the town.

Imported goods included pottery, glass, and luxury items such as silk, Byzantine -style embroidery, and substantial quantities of coins, particularly silver. These imports were rarely distributed to local farms and were generally retained by the town’s merchants.

Birka and the attempts to evangelize Sweden

Much of the historical knowledge about Birka derives from two near-contemporary sources: the Vita Anskarii by Rimbert and the Gesta Hammaburgensis ecclesiae pontificum by Adam of Bremen. Both texts focus primarily on the Christian missions to Birka and the broader region of Sweden.

The Vita Anskarii is a biography of Ansgar, written by his companion and successor Rimbert between 869 and 876. Ansgar, a Frankish monk, was sent to Birka in 829 to promote the Christian faith among the Swedish population. During his journey, he encountered difficulties, including an attack by pirates on the Baltic Sea, which resulted in the loss of most of his possessions, including forty holy books. Much of the remainder of the journey was completed on foot. Upon arrival, Ansgar was received by King Björn II at Hauge, who granted him permission to preach.

Ansgar did not convert King Björn II to Christianity, but he baptized the town’s prefect, Hergeir. After approximately a year and a half at Birka, Ansgar returned to Hamburg, where he became bishop [ fr ], and subsequently sent Bishop Gauzbert and his companion Nithard to continue the mission in the town. Their presence was not universally accepted, and in 845, Nithard was killed, Gauzbert’s residence was burned, and he was forced into exile. That same year, a Danish fleet attacked Hamburg, disrupting Ansgar’s organization, leaving Birka without a Christian missionary until 850 or 851, when Ansgar sent the hermit Ardgar to contact Hergeir, who had maintained his faith. Ansgar visited Birka a second time in 852 or 853, accompanied by Erimbert, Gauzbert’s nephew. After negotiations with the king and the assembly, Ansgar was authorized to preach and to construct a church. Erimbert remained after Ansgar’s departure, and over subsequent years, several priests continued the Christian mission. Following Ansgar’s death in 865, the subsequent history of evangelization in Sweden is sparsely documented. However, Archbishop Unni died at Birka in 936 during a mission, indicating that the archbishopric of Hamburg–Bremen continued to maintain involvement in efforts to convert the Nordic population.

Although the Vita Anskarii and Gesta Hammaburgensis ecclesiae pontificum focus primarily on religious activity in Sweden, they also provide information on the political context around Birka. During Ansgar’s first journey, the reigning king was Björn II, who is reported not to have resided at Birka. Historians generally agree that he most likely ruled from Hovgården. By the 850s, when Ansgar made his second visit, the king was Olof I of Sweden. Between the two visits, a succession dispute occurred between Björn and his brother Anund II of Uppsala, who had been exiled for unknown reasons and sought refuge in Denmark. Anund secured Danish support to reclaim the throne, offering Birka in exchange. The Danish fleet of twenty-one ships joined Anund’s eleven ships in preparation for the campaign. As King Björn was absent from Birka, Hergeir, the town’s prefect, negotiated peace, providing Anund with one hundred pounds of silver on behalf of the inhabitants. Anund subsequently attempted to dissuade the Danes from attacking the town, suggesting that the outcome be determined by drawing lots. The result of the lots indicated that Birka should be spared, and the Danish fleet instead attacked a Slavic settlement.