Sand Spirits are spirits that haunt the South Desert of Elementia. They are spirits of those who have died there, and they now protect the desert from travellers. These spirits do not interfere with anything outside of the desert, so they do not participate in any wars or battles that occur in Elementia.
Since few enter the desert, and even fewer die in it, there is not that many sand spirits living there, but the numbers do grow over time.
Sand spirits have appeared ever since the South Desert was created. When someone dies in the desert, they turn into a sand spirit, forced to forever haunt the desert. This is most likely due to dark magic, and is irreversible.
These spirits stay out of the affairs of the rest of Elementia, and so have not been involved in any wars or battles.