This is the astounding band, First Aid Kit, a sisters-duo from Sweden. In the summer of 2008 they did this cover of "Tiger Mountain Peasant Song" by Fleet Foxes.
"We went out in the forest this morning and recorded this cover of the wonderful song "Tiger Mountain Peasant Song" by Fleet Foxes, our favourite band right now. We saw them live this weekend in Sweden and it was absolutely amazing. If you get a chance to see them live don't hesitate for a second!"