Whereas Neolithic settlers merely exploited the wetlands as they found them, Bronze Age farmers began to modify their immediate surroundings (c.f. Rippon 2000). They started by cutting down thickets and woodlands in order to obtain timber, fuel and fodder. They made ditches to surround their fields and occasionally raised their farmyards in order to cope with increasing groundwater levels. About 1350 B.C., relatively large numbers of colonists settled at a former salt marsh estuary on the Noord-Holland peninsula. A 9th-century B.C. site has been excavated on the banks of the Weser River (Buurman 1996; Hoops Reallexikon, S.V. Rodenkirchen). Both areas were characterized by a freshwater environment. The river banks of the Ems were first colonized during the 7th century B.C., the Elbe River banks at the latest during the 4th century B.C. In each case, settlements were abandoned as soon as forward-pushing mires and recurrent sea-breaches submerged the area. In Roman times, the riverbanks were densely populated: by then, the original elm-ash tidal forest had been largely destroyed (Behre 1995a, 1995b).
The adjustments required for living in the unprotected salt marshes were even more profound, as people had to cope with shortages of fuel, timber, cereals and drinking water, as well as with the risk of storm surges. The first settlers may have been transhumant pastoralists who took their cattle to higher grounds during the winter season (Bierma et al. 1988). Probably the expansion of inland bogs reduced their means of subsistence and made them look for alternatives in the rapidly expanding marshes. The salt marshes were largely treeless, covered by a broad spectrum of habitats ranging from Spartina swards and Aster- and Artemisia-dominated salt meadows to brackish reed swamps, freshwater sedge beds and transition mires, bordered by raised bogs and alder-birch swamp woods (Behre 1985). Intensive grazing and mowing, however, created an open landscape in which black-grass communities (Juncetum gerardi) and Puccinellia grass lawns were the dominant vegetation.
The Fryslân and Groningen coastal marshes were the first to receive permanent human settlement, which took place in the 6th and 5th centuries B.C. The other coastal districts were colonized in the first century B.C., the Schleswig–Holstein marshes somewhat later (Kossack et al. 1984: vol 1; Bierma et al. 1988; Behre 1995a, 1995b, 2001; Meier 2001; Bantelmann 2003). Additionally, the moraine plateaus and outcroppings bordering the Wadden Sea (including the future islands of Texel, Föhr and Sylt) came to harbour large populations. Several barrier islands may have been inhabited as well. Yet archaeological findings are totally absent due to coastal drift.
As a rule, the first salt marsh settlements were established on the surface just above high-tide levels, which were at least 1.25 m lower than they are today. Subsequently, the inhabitants began to raise their farmyards. Only after several generations did they start to build collective raised mounds from sods and dung on which they situated their farms and infields. Occasionally, quays measuring three to four feet in height surrounded the infields (Bazelmans et al. 1999). Step-by-step, the settlers became fully adapted to living in tidal areas, preserving winter stocks of hay, fuel and drinking water, and tilling the stiff clay soil during the brief summer season. Various tribes shared virtually the same technology. They cultivated salt-resistant summer crops, mainly field beans (Vicia faba var. minor) and hulled barley (Hordeum vulgare var. tetrastichon), supplemented by oats (Avena sativa), flax (Linum sativum), emmer wheat (Triticum dicoccum), gold of pleasure (Camelina sativa) and probably kale (Brassica oleracea var. acephala). Ditches radially descending from the village mound and running towards tidal creeks and gullies carefully drained the outfields. The farms, accompanied by helmed haystacks and artisan pit-houses, were located side by side along the slopes of the mound. Alternatively, on the banks of the Elbe River, where the tides were less pronounced, farms were situated on a row of house platforms bordering a tidal creek. The aisled longhouses had roughly the same structure as their Bronze Age predecessors. Cattle were stalled in the side-aisles behind a gutter; the living quarters were located in the adjoining hall. Wells and ponds guaranteed fresh water supplies; dried cow-dung, reed or peat served as fuel; timber, weaponry and querns had to be imported. The coastal farmers were primarily cattle breeders, exchanging their surplus products with the upland villagers or selling them to Roman traders (Kossack et al. 1984: vol 1; Bierma et al. 1988).
The early history of coastal settlement is one of successes and setbacks (Behre 2001, 2003). Sites that had been populated during times of maritime regression were later abandoned because of rising seawater levels and increased storm surge frequencies. Fresh layers of sediment covered the existing salt marshes, forcing the settlers to move towards recently deposited seashore banks or, alternatively, to find refuge on the edges of the raised bogs. The abandoned backswamps turned into peat moors. Particularly during the Migration Period (450–600 A.D.), tribal wars and the introduction of malaria took a heavy toll. The existing population was decimated. A new generation of settlers came from the east, others subsequently moved back, colonizing the Lower Saxon and southern Jutland coasts as well as the western barrier islands. Apparently, the Lower Saxon and Jutland barrier islands had not been settled before the High Middle Ages (1050–1300 A.D.) (Abrahamse et al. 1976).
Basic technologies remained practically the same. The majority of the Early Medieval settlers were ethnic Frisians, who mastered the skills of wetland settlement far better than their Danish neighbours who stayed on higher grounds. Archaeological finds show a rich and diverse material culture, characterized by extensive maritime contacts and a considerable degree of specialization (Schmid 1991; Knol 1993; Heidinga 1997). Next to stockbreeding, sheep breeding and some arable farming, people were engaged in the production of dyed cloth, salt and hides. Trade concentrated on the exchange of foreign luxury products, which were vital for the gift economy of local warlords and their retainers. A new type of trading village came into existence, situated along tidal creeks and populated by merchants, skippers and artisans. In many cases these trading villages developed into centres of political and ecclesiastical power (Kossack et al. 1984: vol 2).
The Frisians were specialists in salt making, for which they burned silted peat as well as eelgrass (Zostera marina) and boiled the ashes. In order to obtain the raw material, they dug off the tidal peat banks, which were more or less systematically destroyed. For 100 kg of salt, at least 4–10 cubic metres of peat or, alternatively, 11 loads of eelgrass had to be processed. The extent of the devastated area is unknown, but it must have numbered thousands of hectares, reinforcing the natural erosion of the tidal bogs. Salt making was introduced in Roman times and became increasingly popular in the Early Middle Ages (600–1050 A.D.). By the end of the Middle Ages most tidal bogs had disappeared. The only remaining salterns closed down in the 18th century (Marschalleck 1973; Oost 1995; Van Geel and Borger 2002).
Most of the coastal villages were largely agricultural. Farm construction probably remained the same as before, but sod walls temporarily replaced the wickerwork, probably because of the depletion of willow carr. Most dwelling mounds had a freshwater pond, often connected to a natural well. The infields were located on elevated mounds, banks and holms, surrounded by ditches and hedgerows. After the harvest these served the sheep flocks as a winter refuge. The outfields were parcelled out into privately owned fields, leaving only the remote meadows and peat moors undivided. Historical evidence about fishing is scarce. The indigenous word for cormorant (Phalacrocorax carbo) meaning ‘beggar, glutton’ suggests that medieval Frisians still considered these birds as serious competitors to man (Sjölin 1961). The usual fishing techniques may have involved reed fences, weirs, pikes, fish-traps and nets made of sea clubrush (Scirpus maritimus). Plaice, flounder and dab were consumed in considerable quantities, but finds of whiting (Merlangius merlangus), cod and haddock give evidence that sea fishery was known as well. Sturgeon (Acipenser sturio) and salmon (Salmo salar) catches seem to have been limited to the major river mouths (Illing 1923).
To a certain extent, the coastal society may be considered as a peculiar socio-ecological niche amidst largely unspoilt natural reserves (Knottnerus 1994). People could make use of abundant natural resources, they had ample opportunities for trade and communication and they were relatively safe from inland human predators. The risks of piracy attacks were considerable, though, but normally the coastal inhabitants were not the passive victims presented in history textbooks. In fact, they were often involved in piracy themselves. Nevertheless, contemporaries did not have any idea about nature. What they saw was a bunch of chances, risks and opportunities. The forces of nature were perceived as an extension of their own social world of friends and foes, something to keep in with or, alternatively, to fight against (Gurevich 1985; Knottnerus 1997).