Icelandic folk music: Langspil (instrument)

Icelandic langspil (instrument)
The Icelandic fretted dulcimer, mainly based on the Norwegian langeleik but also inspired by the Swedish hummel.
The fact that two such distinctive and closely related instruments exist in Norway and on Iceland makes it tempting to speculate they date back to the medieval times when Iceland was a part of Norway. This assumption is not correct though since it's a well documented that the instrument doesn't appear on Iceland until long after time period.
http://www.youtube.com/watch?v=-fwLTLfO_jI