Jomsborg

Jomsborg was a legendary viking settlement in Pomerania, which is located by the Baltic Sea. It's generally disputed whether such settlement existed at all, all of the proofs are coming from later era and from distant Islandia. Contemporary sources mention rather city known as Julin, Jumne or Wolin, which supposedly was city known from Slavic pirates, where also Danes and other Scandinavians could easily found refugee,

Harold Bluetooth had to take refuge from his son here in the late 900s.

See also: Early Swedish Kingdoms, Scandinavian connections to Mieszko I