In 793 Viking raiders first visited the British Isles. In 867 the made a raid on Steonshalch the double monastery at Whitby Abbey. The Vikings probably believed they had discovered a rare black amber when they discovered jet. We see very similar articles made in Whitby Jet as in amber, the main sight of manufacture discovered at this time seems to be Jorvik, the Viking trading centre at York. Rough pieces and finished articles were found in the excavations at Jorvik, but there is also evidence of a manufacturing centre at Dublin also at this period. Some of the best pieces from a craftsman’s perspective have been found in Norway and it seems that the Vikings were taking Whitby back to their homelands for manufacture. Many Viking artefacts from this period show Byzantine influence. The trade networks of the Vikings distributed Whitby Jet far and wide and C12th pieces are known from as far a field as Greenland.