Birka: Viking Age Trading Town on Lake Mälaren (c. 750)

Birka was a Viking Age trading town on the island of Björkö in Lake Mälaren, west of modern Stockholm, which flourished from about 750 to 975. It was Sweden’s most important commercial centre of the period, linking the Baltic with Western Europe, Russia and the Islamic world. Its thousands of graves have made it one of the richest archaeological sites of the Viking Age, and it is a UNESCO World Heritage Site together with the nearby royal estate of Hovgården.

Location and founding

In the Viking Age Lake Mälaren was an inlet of the Baltic Sea, with water levels several metres higher than today. Björkö lay at a meeting point of waterways that led inland to the fertile plains of central Sweden and out to the Baltic. Furs, iron and other goods from the interior could be brought there and exchanged with visiting traders.

The town was probably founded around the middle of the 8th century, perhaps on the initiative of a local king. Across the water, on the island of Adelsö, Hovgården was a royal estate with large burial mounds, where the king’s representative may have controlled trade and taxes. Birka was one of a group of new trading towns that grew up around the North Sea and Baltic in this period, alongside Hedeby in what was then southern Denmark, Ribe in Denmark and Kaupang in Norway.

The town and its defences

The settlement covered an area of about 7 hectares on the north-west of the island, known today as the Black Earth because of its dark soil, rich in charcoal and waste from centuries of occupation. Houses, workshops and jetties lined the shore. Craftsmen worked bronze, iron, antler, bone and glass beads, and finds of moulds and waste show large-scale production.

The population was probably between about 500 and 1,000 people at its height, though estimates vary. In the 10th century the town was protected by a rampart with gates on its landward side, and by a hillfort called Borg on a rocky height to the south. Excavations near the hillfort have uncovered a garrison area with a large hall and many weapons, suggesting a permanent armed force.

Trade and contacts

Birka’s finds show contacts across a vast area. Thousands of Arabic silver coins, called dirhams, reached Birka through the river routes of Russia from the Abbasid Caliphate and Central Asia. Silk fragments came from Byzantium or further east, while glass drinking vessels came from the Rhineland and fine cloth from Frisia.

In return, the region supplied furs, slaves, iron and other northern goods. Scandinavian traders, often called Rus in eastern sources, travelled along the Volga and Dnieper to markets in the Islamic world and Byzantium. Birka was one of the places in the north where this silver and these luxury goods arrived.

One small find shows how far these networks reached. A woman’s grave contained a silver ring set with a violet glass stone bearing an Arabic inscription, usually read as “for Allah” or “to Allah”. A study published in 2015 showed that the ring had seen little wear, suggesting it may have come to Birka with few owners in between.

Ansgar’s mission

Birka is the only Swedish town of its time described in detail in written sources. The main text is the Life of Ansgar by Rimbert, written in the later 9th century. It tells how envoys from the Swedes asked the Frankish emperor Louis the Pious for missionaries, and how the monk Ansgar travelled to Birka around 829-830. On the way his party was attacked by pirates and lost most of its possessions.

At Birka Ansgar was received by a king named Björn and allowed to preach. A royal official called Herigar was baptised and built a church on his own land. After Ansgar returned home, a bishop named Gautbert was sent, but he was driven out around 845. Ansgar, by then archbishop of Hamburg-Bremen, made a second journey around 852 and obtained permission from King Olof to continue the mission. In practice Christianity made slow progress, and Sweden was not converted until long after Birka’s end.

The graves

Around the town lie several cemeteries containing an estimated 3,000 graves, the largest Viking Age burial ground in Sweden. The biggest is Hemlanden, east of the town. Many graves are marked by low mounds, while others were cremations or burials in wooden chambers.

The Swedish archaeologist Hjalmar Stolpe excavated about 1,100 graves between 1871 and 1895, and his finds, now in the Swedish History Museum in Stockholm, remain central to Viking studies. Rich chamber graves contained weapons, horses, jewellery, silk, scales and weights used by merchants, and imported vessels.

The most famous is grave Bj 581, a 10th-century chamber grave with a sword, axe, spears, arrows, shields, two horses and a gaming set. It was long assumed to be the burial of a male warrior. In 2017 a genomic study led by Charlotte Hedenstierna-Jonson showed the skeleton to be biologically female. The finding has been widely discussed: some scholars accept her as a warrior, while others argue the objects may reflect status or symbolism rather than her role in life.

Decline and abandonment

Birka was abandoned around 975. Possible causes include the slow rise of the land after the last Ice Age, which made the old waterways shallower; a fall in the supply of Islamic silver in the later 10th century; and political change. The new town of Sigtuna, founded around 970-980 on the northern part of Lake Mälaren, became the royal centre and took over Birka’s role.

Archbishop Unni of Hamburg-Bremen died at Birka in 936 during a missionary visit. By the 1070s, when the German chronicler Adam of Bremen wrote his history of the archbishops, Birka was described as deserted, with its location already hard to identify.

Rediscovery and research

After its abandonment Birka was gradually forgotten, and for centuries scholars argued over where Rimbert’s town had stood. From the 17th century Björkö was proposed, and the many mounds and the Black Earth made the identification increasingly certain. Stolpe’s excavations in the late 19th century settled the question.

Modern research has used new methods. Large excavations in the Black Earth between 1990 and 1995, led by Björn Ambrosiani, recorded house plots, workshops and harbour structures layer by layer. Later work around the hillfort and the garrison, together with isotope and DNA analysis of skeletons, has shown that some of Birka’s inhabitants grew up far from the Mälaren region, underlining its role as a meeting place.

Today Björkö is reached by boat from Stockholm in summer. A museum with reconstructions of houses and a model of the town opened in 1996, and the island remains largely rural, with the remains of the town and its cemeteries protected as part of the World Heritage Site.

Timeline

• c. 750: Birka is founded on Björkö in Lake Mälaren.
• c. 829-830: Ansgar’s first mission; Herigar builds a church.
• c. 845: Bishop Gautbert is driven out.
• c. 852: Ansgar’s second visit to Birka.
• 936: Archbishop Unni dies at Birka.
• c. 975: Birka is abandoned; Sigtuna rises as the new centre.
• 1871-1895: Hjalmar Stolpe excavates about 1,100 graves.
• 1993: Birka and Hovgården are inscribed as a UNESCO World Heritage Site.
• 2017: DNA study shows the Bj 581 warrior grave held a woman.

Why it matters

Birka shows how Scandinavia was tied into a trading world stretching from the Atlantic to Central Asia in the same era that saw raids such as the Viking raid on Lindisfarne. Its graves, crafts and imported goods reveal everyday Viking life beyond the familiar image of raiders, and its role in Ansgar’s mission marks the beginning of Christianity in Sweden.