Spirits of the mound are one direct foundation of elf and fairy belief. But, the connection may have also come about indirectly by the demotion of pagan gods during the conversion to Christianity.

It has been noted that belief in “small spirits” continued on in folk belief for hundreds, and in some cases even a millennia, after conversion. The epic gods may have been diminished into smaller spirits of the land.

By small, I don’t necessarily mean stature. But their power and roles were lesser than the mighty and central role that the great gods once played. For example, the Irish gods of the Tuatha De Danann were later associated with fairy lore.

Even into the modern era, fairies continued to be associated with the dead. In fact, some folklorists have noted that in folk accounts, there isn’t a clear differentiation between ghosts and fairies (Spence, 87).

The Otherworld inhabited by fairies was often associated with the land of the dead, and spirits of dead relatives and ancestors were often said to be existing in the land of the fairies.