This is a very exciting idea and I think it wouldn't be too far of a stretch for them to be from Vana and I think that FFXI and FFXIV might take place in the same mythos/universe as each other just like how FFXII and the Tactics games are part of the same mythos/universe and I think FFXIII, FFXV, and... fack I think it's called Type-0. It was a psp game that only released in japan and I forget the name! Anyways I remember a while back when 13 was still being worked on that those 3 games were part of the same mythos/universe.
With that said I'd also like to explore another possibility! Could it be possible that the Mamool Ja are just from another part of Hydaelyn that maybe use different terminology? Eorzea to them could be like living on a completely different world. You also made mention of a Great Empire to the east. Now this could be reference to Aht Urhgan but it could also mean the Garlean Empire since the realm of Eorzea is found on Hydaelyn's western most continent along with islands. So that leaves 2 more great continents along with anything else that might be out there.
I still think it would be a little fantastic if the Mamool Ja actually did come from Vana though and that raises the question about the goblins and such.
With that said I'd also like to explore another possibility! Could it be possible that the Mamool Ja are just from another part of Hydaelyn that maybe use different terminology? Eorzea to them could be like living on a completely different world. You also made mention of a Great Empire to the east. Now this could be reference to Aht Urhgan but it could also mean the Garlean Empire since the realm of Eorzea is found on Hydaelyn's western most continent along with islands. So that leaves 2 more great continents along with anything else that might be out there.
I still think it would be a little fantastic if the Mamool Ja actually did come from Vana though and that raises the question about the goblins and such.
