The wider availability of metal tools contributed to agricultural expansion and a rising population, and an increase in conflict. In the late second century BC population pressure led directly to the first of what would be many migrations out of Scandinavia. Faced with a critical shortage of farmland, around 120 BC two tribes from northern Jutland, the Cimbri and the Teutones, set out on a migration in search of new homelands. Their search took them on a destructive rampage across much of central and western Europe before they invaded Italy in 102 BC and were finally annihilated by the Romans. Although it ended in disaster, this migration was just a foretaste of what was to come. Many of the Germanic tribes who invaded the Roman Empire in the fifth century traced their legendary origins to Scandinavia. The Goths believed they had originated in Götaland in southern Sweden; the Burgundians from the island of Borgundarholm, now Bornholm in Denmark; and the Vandals from Jutland. The Angles and Jutes, who joined the Saxons in settling Britain, both certainly came from Jutland. Writing around 550, the Gothic historian Jordanes described Scandza as ‘the womb of peoples’ because it had given birth to so many tribes. The Viking expansion was really just the last phase of an extended period of migrations out of the north.
Conflict is the essence of what is possibly the single most important archaeological find of the early Iron Age: a near-complete ‘war canoe’ and a hoard of weapons that were buried together in a bog at Hjortspring on the Danish island of Als around the time of Pytheas’ travels. The boat itself is the oldest plank-built boat yet found in Scandinavia and has enormous significance as the earliest known ancestor of the Viking longship. What is immediately most striking about the Hjortspring boat is its distinctive double beaked prows, which closely resemble those of the boats depicted in the Bronze Age petroglyphs, so it is likely to represent a well-established tradition of boat building. The boat was 56 feet (17 m) long by 6 feet (1.8 m) broad and was built from just five lime wood planks: a broad bottom plank with two overlapping planks on each side. This method of building a hull from overlapped planks, known variously as clinker, lapstrake or Nordic construction, is what marks the Hjortspring boat out as the earliest known ancestor of the Viking longships, whose hulls were built in the same way. The ends of the Hjortspring boat were closed with two carved wooden blocks that served as stemposts. The function, if any, of the projecting beaks is unknown. They may have been intended to ride up over the gunwales of an enemy boat and capsize it, or they may simply be a hangover from an earlier stage in the development of the Nordic boat-building tradition that were retained for cosmetic reasons: they do give the boat a racy appearance. No metal was used in the boat’s construction: the planks were sewn together and fastened to internal strengthening ribs with ropes made of lime tree bast. The boat was paddled by a crew of twenty – a useful number for a raiding party – who sat on thwarts set at the level of the gunwale. There was a steering oar at both ends, so the boat could be sailed in either direction. This would have been a great advantage for raiding because the boat could run right up a beach and the crew would not have had to turn it around if they needed to make a quick getaway. The boat was skilfully built to be as light as possible and sea trials with a replica have shown that it was fast, stable and relatively seaworthy. The boat was sunk in the bog with enough weapons to equip a small army: 138 iron tipped spears, thirty-one bone- or antler-tipped spears, eleven iron swords, sixty to eighty shields, and around twenty coats of mail, all but one of which survived only as rust prints in the peat. Plates from a bronze cauldron and the bones of a horse, a dog and a puppy, a lamb and calf were also found. Both ship and weapons survived thanks to the acidic and anaerobic (oxygen deficient) conditions found in peat bogs, which preserve organic materials like wood, textiles and leather by pickling them, while the lack of oxygen retards the rusting of iron.
The Hjortspring find is one of the earliest examples of a practice of sacrificing the spoils of war that became widespread in Scandinavia and adjacent areas of north Germany during the early Iron Age. No other known sacrifice approaches the Hjortspring find in scale, however, and its deposition must commemorate a major battle. The most likely scenario is that the ship and weapons belonged to a large army that invaded Als only to be defeated by the local inhabitants, who offered their plunder to their gods as a thank-offering for victory. There are enough weapons to equip at least eighty warriors, so the invaders would have needed a fleet of at least four Hjortspring-type boats and, of course, we don’t known how many of them escaped. It is clear, at least, that raiding by sea was already a serious business in early Iron Age Scandinavia.
It was not only weapons and boats that were sacrificed in bogs, people were too. No bog bodies have been found in Norway or Sweden but over 200 have been found in Denmark and neighbouring areas of northern Germany. Though the acidic conditions in the bogs have often completely dissolved the victims’ bones, in many cases their hair, skin and internal organs are so well-preserved that post mortem examinations have revealed much about their health, diet and causes of death. One surprise is that seafood appears not to have been an important part of the Danish diet in early Iron Age times. Most bog bodies show signs of a violent death, like Tollund Man, killed c. 400 BC by hanging, and Grauballe Man, whose throat was cut from ear to ear around 100 years later. Some of the victims were found pinned down in the bogs by heavy branches. In Germania, a treatise on the Germanic peoples written in AD 98, the Roman historian Tacitus says that this was one of the methods used by the German tribes to execute criminals.
The warlike character of Scandinavian society intensified in the course of the Roman Iron Age. Many Roman weapons have been found in votive hoards, especially in Denmark, suggesting that Scandinavians frequently fought with their German neighbours to the south, who had direct access to Roman weaponry. The increasing importance of war in society is indicated by the appearance of warrior graves furnished with weapons, evidence that a warrior elite now dominated Scandinavian society. A small number of these graves are furnished with imported luxury goods, such as Roman silverware, jewellery and glass, indicating the rise within this elite of a class of chieftains or petty kings. Everyday Roman goods, like pottery and coins have also been found in some quantity in Scandinavia, show that trade with the Roman Empire was not confined to luxuries. There may have been direct trade with the empire by sea, but it is perhaps more likely that Roman goods reached Scandinavia through intermediaries in Germany. Not surprisingly, Roman artefacts are most common in Denmark, but they are not evenly distributed over the country. One remarkable concentration of Roman goods is found in the Stevns area of the island of Sjælland, suggesting that this was the centre of a powerful chiefdom or small kingdom, which could control trade over a wide area. Another striking site from the later part of the period is Gudme on the island of Fyn, where evidence for a 154-foot (47 m) long hall has been found: the largest known in Scandinavia from this period, it has been called ‘the King’s Hall’ and, certainly, a hall of such size implies the existence of a strong central authority. Over 1,000 Roman coins, including twenty gold denarii, have also been found at the site. Gudme means ‘god’s home’, so the place may have been a cult centre. Closely associated with Gudme is a seasonal port and trading place at Lundeborg, where Roman coins and other imports have been found, along with evidence of shipbuilding. This close association between religion and trade is also seen at the Iron Age trading place at Uppåkra near Lund in southern Sweden, where the remains of a wooden temple have been found. It is likely that trade fairs were held during religious festivals when plenty of visitors could be expected.