Vikings acquired the capacity to produce tar at an industrial scale as early as the 8th century AD, according to new research.
The protective black goo was applied to the planks and sails of ships, which the Vikings used for trade and launching raids.
By the 16th century, Europeans had developed a technique whereby piles of wood, placed in funnel-shaped pits, were burned slowly under an oxygen-constricting layer of an earth-clay mixture and charcoal.
New research published today in the journal Antiquity is shedding new light on this unanswered question, revealing a unique method of tar production previously unknown to scientists.
The lone author of the new study, Andreas Hennius from the Department of Archaeology and Ancient History at Uppsala University in Sweden, documents the discovery of large tar-producing pits in the Swedish province of Uppland.
These tar pits were located several miles away from villages, likely due to their closer proximity to an essential ingredient of tar production: forests filled with wood.