It seems to be mentioned in The
Saga of
Erik the
Red, an Icelandic story written in the 13th century and set in the 10th and 11th centuries. There
Leif Eriksson, who discovered
America, is given two Scottish slaves, a man called Haki and a woman called Hekja, by the Norwegian king
Olaf Tryggvason. I can't find anything on the meaning though.