Ayi, the moon, was created by the 4 gods of the moon. They intended to create a peaceful mini planet, where people got along. One of the gods was consumed by corruption, and ruined the creation ceremony; as a result, the gods disappeared, leaving the moon open to corruption.
A group of wandering spirits decided to take over, and they named themselves the Guardians (Eldas), claiming they were sent by the gods to watch over Ayi. This was false information, and in truth they just wanted to experiment on the inhabitants of the moon. Being dead, they wanted to come to understanding the nature of the inhabitants a little better; which is why they experimented on them.
This is why the Soman Treasure was created, to teach the people that wishing was counter-productive and actually dangerous.
It is unknown where the Eldas originated from, but some believe that they are actually deceased mobians of times past.