Layans and Orakians
Well, well... we can say that it's a matter that offers you a huge variety of opinions (as well as many others). As you can see, I don't have a theory, I have more than one. However, I don't think they can be "true". Note that they aren't in order of preference.
Theory N° 1: Mother Brain is the image of Laya, Rolf is the one of Orakio.
Let's say that after destroying the Mother Brain, Rolf and the others simply disappeared. No one knows anything about them. After a while, people thinks they must have someone to convert in a specie of "God/Goddess". The ones that liked the style of life that Mother Brain created, turned into what later were known as the followers of Laya. The ones that agreed with Rolf, turned into Orakians.
Possitive Points: Mother Brain was "female". Rolf had prestige (as well as he was hated) in Paseo (and I suppose everywhere, after killing the MB).
Negative Points: Ouch! Lots!! 1- Rolf had techniques, the Orakians hadn't. 2- What about their companions? (Miun, Lune, Alair, little Laya, etc...) 3- Laya was a real person. 4- Laya created mosters, MB had robots.
Theory N° 2: Layans were Palmans, Orakians were Earthmen.
It could be, it could be... The Earthmen decided to take Algo by the force, so they needed "spies", to know about the life in Algo (to be exactly, Palma). They settled like a "colony" all over Palma. That colony grew, and grew, and they could pass as natives. That way, they could kill the Palmans that were on the ships that escaped form Palma, and to have like an army to fight against the natives, just to take possession of the planet (or the ship). By that method, the conquest of both Motavia and Dezoris would be a piece of cake (or shortcake, in the PS universe :). As Palma was destroyed, they continued their "conquest" in the ships.
Possitive Points: The Earthmen don't have techniques (at least, we don't have), the Orakians had technology (thing that also had the Earthmen). In Rysel, a woman says: "We minstrels know much of the ancient legends. My favourite is one that tells of our people fleeing a terribly evil thing called Dark Force! The legend says we are the last survivors of a race that sailed between the stars." With this, we can say that they were Earthmen! They have been sailing between the stars, they had a Dark Force, they don't have Techniques...
Negative Points: But the same speech can make my theory false, because the woman could have been talking about the whole Alisa III, not about the Orakians...
Theory N° 3: Laya was an Esper, Orakio, a normal guy.
Well, somehow, they both met, and the fight starts. Or maybe Orakio was the ruler of somewhere, ans Laya decided to attack him... I don't know (that could be another theory, but I don't have ideas about the beggining of the Layan-Orakian War...)
Possitive Points: Both Espers and Layans have techniques (Espers have true magic),
Negative Points: Normal Palmans have techniques (or maybe the Layans have true magic and the Orakians, techniques; maybe they hadn't developed them, or their genetic code was modificated by something (or someone),
Theory N° 4: The Layans had true magic, the Orakians lost the ability.
This one has a very strong relation with the previous one. Maybe Layans could use true magic or techniques, while Orakians had lost their ability. Somehow, but they lost it. Or they didn't know how to use it.