Excavations at Sangis, 1,000 kilometres north-northeast of Stockholm near the Gulf of Bothnia, uncovered a rectangular iron-smelting furnace comprised of stone slabs with one open side, and holes in the frame for blowing air onto burning charcoal. A clay chimney had been built in and partly on the frame. Inside the furnace were remnants of a ceramic wall lining, and slag from heating iron ore.
     Radiocarbon dates show the site was active between around 200 BCE and 50 BCE. Pottery fragments and other material were discovered about 500 metres from the furnace, dating to between around 500 BCE and 900 CE. Other finds include numerous fish bones, at least three fire pits where iron was reheated and refined, as well as several iron items, others of steel, a bronze buckle, and metallic waste with copper droplets on the surface. The casting and decorative style of the bronze buckle resembles metal items found at sites in northwestern Russia dating to as early as around 2,300 years ago. Knives and other iron objects found at Sangis contained two or more layers that had been expertly welded together, and had in some cases been heat-treated to improve their strength.
     Other excavations at Vivungi, about 260 kilometres further north, uncovered remains of two iron-smelting furnaces in use from around 100 BCE. Radiocarbon dates of animal bones found near the furnaces indicate repeated occupation from around 5300 BCE to 1600 CE.
     Supposed by many to have been an invention of large agricultural societies in southwest Asia more than 3,000 years ago, evidence of iron production more than 2,000 years ago is known in southern Scandinavia, and preliminary study suggests iron was also being produced in East Asia at that time.

Edited from Science News (3 January 2022)