Vikings used the process known as riving to reduce a tree trunk to planks. Rather than sawing the wood, they split it. As a result, the grain of the wood follows the piece being fabricated, creating a much stronger item than if it had been sawn. It's one of several reasons why thin-hulled Viking ships could withstand the rough seas of the North Atlantic http://www.hurstwic.org/history/articles/manufacturing/text/viking_woodworking_riving.htm
Many historians commonly associate the term “Viking” to the Scandinavian term viking, a word for “pirate.” The term is meant to reference oversea expeditions, and was used as a verb by the Scandinavian people for when the men traditionally took time out of their summers to go “a Viking.” While many would believe these expeditions entailed the raiding of monasteries and cities along the coast, many expeditions were actually with the goal of trade and enlisting as foreign mercenaries.