My understanding is that Vaegirs ruled all of Calradia, and then the what we now call Swadians came in and took over the western half, if the north was the Trirumvirate ocean, forcing the Vaegir to move their HQ to Reyvadin.
I have an explanation for Zendar being neutral. Although, yes, it is now neutral because it keeps the economy of both sides running (just where do you think they get all of the weapons? by trading tools and stuff!), did they attack it before? Yes indeed! Since it is one of the cities on the halfway point between Swadia and the Vaegir, they were constantly attacking it, and was always changing hands.Of course the Vaegirs had the advantage in holding it because it was on THEIR side of the river, but the Swadians, with Praven being close enough, could just make a sortie and capture it. Fact of the matter is, is that it was ransacked so many times, it became nothing more then a pile of rubble. It was utterly useless now to any of the armies who were to besiege it, and was possible just a death trap. So, it was abandoned. Then, refugees from both sides decided to make it their city, and many people came and rebuilt it. They built up their own militia, and declared themselves neutral. They elected Arrasies as Count, because he was one of the first to come and rebuild, and was known to be quite handy with a weapon in a pinch. He secretly stole Army weapons, and built very high walls, so that in the inevitability of an attack, they could defend it. And attacked it was. Both Swadians and Vaegirs tried to conquer it, but by this time the city had quite a large force for one city, and being on the crest of a hill, was giving it's defenders an added defense bonus. Attacked it was, but the attackers failed time and time again. Count Arrasies and his men killed many good soldiers from both sides, and claimed self defence, whilst plundering the dead of good weapons and armor. So, the two side coincidentally agreed that Zendar should remain neutral. And then, Count Arrasies created a port for trading ships, and now it is the Zendar we know today, where many people from many nations come and trade their goods.