What Doshii said is kind of what I meant in my first post. What I think the Azoreans lack is a means to properly convey how their civilization progressed and what technologies they have adapted to their unique lifestyle.
An advanced underwater society isn't easy to think up of, I realize, but that's why we should get together and brainstorm further (by that I mean you [dusk], me and Fay, as we've done once or twice before). We have to come up with a progress tree for the Azoreans so that we can clearly identify how Azorean society lives.
I understand that making a Role Play in history would probably make it easier to picture, but we're still going to come up with nearly everything before we RP, regardless at what point in time we RP the Azoreans, because a society of a water-breathing population is radically different to a terrestrial society regardless of what point in time we focus on.
Everything changes. The most rudimentary things like writing, metallurgy, waste disposal (that's right, I'm talking about what comes out your rear end), hygiene, become impractical and/or impossible and you've got to take that into account. In fact, one could say the further into the Azorean past you go, the more radically different it is from a terrestrial society's culture of the 'same technological level'.
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To make a long story short, my point is that before you make a plot in the past, you've got to make quite a bit of background work anyway. So if you're going to use the plot to set up a ground upon which to work for future plots, you've still got a shitton of work ahead of you, and the further into Azorea's past you go, the more different it will be from a terrestrial civilization. The more different an alien culture is from a culture you're used to, the harder it is to Role Play that alien culture (I should know; playing Iroma and Freespacers is a challenge).
So I think making a plot about the past is a bit impractical, and while it's understandable that you want the Azoreans to have an enemy to face in the plot, it doesn't have to be in the past just because you want it to be in the same planet. A present plot doesn't have to focus on space, after all (example: Land of Dreamers).