Björn Ironside (Old Norse: "Bjǫrn Járnsíða"; Icelandic: "Björn Járnsíða"; Swedish: "Björn Järnsida"; Danish: "Bjørn Jernside"; Medieval Latin: "Bier Costae ferreae") was a Norse Viking chief and semi-legendary king of Sweden, who appears in Norse legends. According to the 12th- and 13th-century Scandinavian histories, he was the son of the notorious and historically dubious Viking king Ragnar Lothbrok. He lived in the 9th century, being securely dated between 855 and 858. Björn Ironside is said to have been the first ruler of the Swedish Munsö dynasty. In the early 18th century, a barrow on the island of Munsö was claimed by antiquarians to be "Björn Järnsidas hög" or Björn Ironside's barrow.