Jomsvikings were a company of Viking mercenaries of the 900s and 1000s, dedicated to the worship of such deities as Odin and Thor. They were staunchly pagan, but they reputedly would fight for any lord able to pay their substantial fees, and occasionally fought alongside Christian rulers. According to the Norse sagas (particularly the Jómsvíkinga saga, King Olaf Tryggvasson’s Saga, and stories found in the Flatey Book), their stronghold Jomsborg was located on the southern shore of the Baltic Sea, but the location is disputed by modern historians and archeologists. Nordisk familjebok asserts it to be located on the eastern side of the island of Wollin, on the hill Silberberg north of the town Wollin.
The legend of the Joms appears in some of the Icelandic sagas from the twelfth and thirteenth centuries. The existence of Jomsborg is a matter of debate in historical circles, due to the scarcity of primary sources. There are no contemporary sources mentioning the names Jomsvikings and Jomsborg, but there are three contemporary runestones and several contemporary lausavísur held to refer to one of their battles.