One commodity which the Vikings traded consistently was slaves. In addition to slaves, the Vikings offered honey, tin, wheat, wool, wood, iron, fur, leather, fish and ivory.
The Vikings often captured slaves on their raiding expeditions. These were important because there was almost always a market for human labor throughout the world, and they fetched very good prices. The Vikings' trading ventures took them all over the globe; thus, the items that they traded and received in return varied depending upon where they landed. Cod in particular became a favorite trade offering of the Vikings as they developed new ways of drying and preservation which kept their product fresh on longer sea voyages. This meant that they could broaden their trading market throughout Europe. In return they wanted items which they could not easily produce on their own, such as silks, exotic spices, wines, glass, amber, jewelry and pottery. Viking traders usually carried portable scales with which they could weigh coins to ensure a fair deal. The Vikings' business did not always involve sea travel; they established lucrative trading towns in their own Scandinavia. They even set up such towns in England and Ireland and were very prosperous. York became one of the most active trading cities in England thanks to the Vikings, second only to London.