A term used by the Dwarf Glóin, when recalling the wonders of Moria, the lost mountain city of the Dwarves. Moria, or Khazad-dûm, had been the greatest of the Dwarf-cities, spreading beneath the central Misty Mountains and ruled over by Kings of Durin's line. That kingdom had been lost to Durin's Bane, and the Dwarves had been driven out of their ancient home more than a thousand years before the War of the Ring.

The extent of the 'Northern World' is uncertain, and indeed it may well be that Glóin himself had no particular boundaries in mind, and was simply making a general reference to the northern lands of Middle-earth. It may be relevant, however, that according to the traditions of the Dwarves themselves,¹ the power of Khazad-dûm had at one time extended over a wide area of northern Middle-earth, and it is perhaps to these old holdings that Glóin was referring.

At their greatest, during the First Age, the lands under the influence of Khazad-dûm encompassed the eastern Misty Mountains and the Vales of Anduin, as well as the lands along Ered Mithrin, the Grey Mountains, as far eastward as the Iron Hills. These lands would later be greatly reduced by incoming Elves and Men, but they perhaps indicate the bounds of the 'Northern World' as a Dwarf of Durin's Folk might have imagined it.