From ore and forestry to iron and steel

Iron has been produced from bog iron ore in Mid-Norway since at least 400 BC. The smelting technology has changed since this period from an intensive initial phase lasting from 400 BC to 500 AD to small-scale production in the late Iron Age/Medieval period and finally a different type of technology was used from 1500 AD to 1700 AD, which is described in written sources. The various technologies reflect the different social and economic conditions. In some areas, the production led to deforestation and permanent changes in the natural environment. The production of iron in outfields has during different periods required advanced organization. During the early Iron Age, an average production site required a labour force of between 10 and 15 people. In some remote areas, several production sites were operated at the same time and local communities were unable to recruit enough people. Regional chiefs seem to have organized expeditions, supply of labour and trade of iron during this period. In Medieval times, local iron producers seem to have responded to a new demand for iron from the City of Trondheim, which was founded in AD 997. Production and supply of iron seems to have been interrupted by the climatic disaster of AD 536 and the Black Death in AD 1349. Knowledge of processes and markets disappeared after these events.