When Link ventures into another dimension (which could well by the Dark World -- note the trees in the fourth screen) to locate the missing Rod of Seasons, he encounters the Ulra Tribe. Not to be confused with the elderly Ulrira of Link's Awakening, the Ulra Tribe is a band of cloaked midgets living inside a volcano on the continent of Ulra.

   It seems the Ulra Tribe uses only a barter economy, so Link will have to trade for whatever he wants from these quirky characters. Fortunately, many commonplace items from Hyrule are considered rare and valuable in Ulra. Additionally, their many years of living in and around a volcano make the Ulras excellent blacksmith -- perhaps they'll be able to refine Link's sword.