They were just some random tribe formed in the Age of Ice from refugees from various nations with only one thing going for them: Eve (named Epona in that life) was reborn among them, and Kyorlin wanted to protect his wife at all costs. Not all Amurites are descended from Kyorlin, but a lot of them are as he took many, many wives. The best mages from other societies immigrated here to study under the masters, so not all of their magical aptitude comes from Kyorlin.
They have taken up a lot of the old ways of Patria. Dain was the first to pass the ancient tests to become the Cassawallen (strongest mage/head of the mage guilds and military), but he didn't have to defeat the old Cassawallen because there was none at the time. He is the most powerful wizard in Erebus (assuming Kyorlin isn't still around, and probably excluding Perpentach whom I suspect was a Cassawallen in the Age of Magic, as only Perpentach ever defeated Kyorlin in magical combat), but his mind wanders and he not a good administrator. He is generally a good natured and ethical man, but he was battle hardened in his youth and to have risen aven to be an archmage (which one must be to take the tests to become a cassawallen) he must be extremely pragmatic too. He is almost certainly a direct descendent of Kyorlin and Epona.
The Amurites are a Republic, but not really in the modern sense. It is dominated by the mage guilds, which form a non-hereditary aristocracy/senatorial caste that dominates society. The mage guilds recruit all small children who show magical potential, and require they cut all ties to friends and family. The families cansider this a great honor, but since it is illegal to track what family an adept comes from they will never see their children again, or know it if they do. The tasks that adepts must perform are more dangerous that those for mages and archmages, so a high percentage of them die before puberty.
I believe that they do elect their civilian government, but that these officials ether are elected to serve for life or have enough influence to prevent any rivals from being able to defeat them in any reelection. Valledia is a very shrewd politician who was elected Queen, and now subtly exercises more power than most despots. Valledia is not a powerful sorceress. She is below average for an Amurite (at least for the upper class), albeit probably still a pretty good mage by non-Amurite standards. I think that she came from a family of commoners and was not deemed gifted enough to be taken away from them. She is not an egotistical megalomaniac, but she is ruthless and wields great political power. She has no qualms about breaking the law for the good of her people. She illegally tracks the bloodlines, and she freed the convicted necromancer Samael in exchange for placing a horrible curse of Einion Logos's wife. His runes bound her soul in her flesh so she could not die and drove her mad so that she tried repeatedly attempted suicide and cursed her husband. It was made to look like a demonic act, so that the Elohim would not honor their treaty with the Infernals because she figured that her nation was the weakest and most likely next target for the Infernals. When her diviners showed that the Elohim would rejoin the war but not soon enough, she called for her people to welcome The Order.
I tend to think that Dain would favor the Empyrean, and Valedia the Council of Esus.
The magical aristocracy doesn't like Govannon since he teaches magic to those who have not passed their screening and indoctrination and could challenge their authority, but since he is as strong as any of them they can't do much about it. Valledia also realizing the benefits of having the whole army know magic, so she tacitly supports him. She likes that his teachings help keep the aristocracy too weak to oppose her. I suspect that he tries to devote himself to teaching the poor rather than the military, but that Valledia may get her most loyal military officers to pretend to be paupers around him so that he is boosting her power instead of actually helping the poor.