Well, I've been daydreaming, and an idea popped in my mind. I had been thinking about Hearth's Warming Eve and how the species of ponies were divided. And that got me to think, what if they were divided again? What if a war had started amongst them? These are my ideas:
The Unicorns have control over Canterlot, which includes the castle. I'm not sure what I can do about Celestia and Luna being there, though. The unicorns can use magic to their advantage in the war, and unicorns are being trained in Canterlot on how to do complex magic. The laws are strict in Canterlot and you can be easily executed if you do not follow them.
The Pegasi have control over Cloudsdale. They can use flying and control over weather to their advantage. If you are not a strong pony and/or are not willing to fight, you get kicked out of Cloudsdale. Only the strongest of pegasi are allowed in Cloudsdale.
The Earth Ponies have control over Ponyville and Appleloosa. They are strong and courageous, and use that to their advantage. There are many of them, but not all of them fight in the war. The Earth Ponies are more civilized and kind, so if you are not willing to fight you don't have to. You can just live a happy life.
I've never started an RP before, and I think this is too small of an idea for one to be based off of. Anypony have an idea about what I could add to make this RP worth making?