There are many possible influences for Tolkien’s ring of power. The first and most obvious is the magical ring of the Norse Völsunga Saga and later Germanic Nibelungenlied. In these, a ring called Andvarinaut is cursed by the god Loki to bring tragedy to whoever possesses it. The ring is desired by everyone, causing much conflict, but it only brings unhappiness. In the same story there is also a broken sword that is re-forged, something that will appear later in Lord of the Rings.
Wagner’s Der Ring des Nibelungen, a cycle of four operas based on the Völsunga Saga and the Nibelungenlied, also features the magical, cursed ring. Some critics have seen major similarities between Wagner’s work and The Lord of the Rings, but Tolkien himself denied this influence, saying that “both rings were round, and there the resemblance ceases.” Tolkien did not consider Wagner’s operas to be a particularly good interpretation of the Germanic mythology. However, this has not prevented some modern scholars and critics from concluding that Tolkien must have been influenced by Wagner, whether consciously or not, as many elements of their work are so similar. Others argue that this is a natural consequence of using the same source material.
Magical rings can be found in many different stories and legends. Other items of power are very common too. The Finnish national epic, the Kalevala, tells of a magical artifact called the Sampo, which brings good fortune to its owner. The Sampo is fought over by good and evil, until it is eventually destroyed. Tolkien was very impressed with the Kalevala and has stated that it influenced him in the creation of Middle-earth.