Vikings sold cheap copies of their sword called the Ulfberht. Their original Ulfberht was made from steel imported from the Middle East. Apparently they found a market for their swords and made copies from cheaper metal and sold them across northern Europe, where archaeologists would find them around a millennium later. Today the swords are described as having been too soft and as having buckled or broken easily when used in battle. 21st century researchers say that by the 11th century, after the Russians blocked access to the Volga River, it became almost impossible for the Vikings to obtain the higher-quality steel that they used in making their swords.