sentences:  Further details on his family background are provided solely by the Icelandic and Norwegian sources of the 12th and 13th centuries, which are of limited and uncertain historical value and should therefore be treated with due circumspection.Harald 'Fairhair' is usually portrayed as a polygamous and fertile king, the number of his sons varying between 16 and 20.While Eric's mother remains anonymous in the synoptic histories ("Ágrip") and most of the Icelandic sagas, the "Heimskringla" ("c".