Amestris is Unitary State or tribe built upon the coming together and gathering of all Hain, Human and Roavik tribes in the land between the Ironheart Mountians and the White Sea. Its leader, or Énas, Amartía, built the nation with his own two hands through corruption and unity. With the creation of the Cult of Sin, which spreads throughout the Purple Sands, and in secret in the Roavik, he was able to spread is name and worship of him. This in conjunction with the corruption of Human and Hain chieftains and the Roavik council men which he called the Illumi, he was able to set a plan in motion that would unite the land and its population under his control.
Amestris, run by an early form of a Parliamentary Republic. The Head of State is the Commander-in-Chief of the Military who holds the title of "Énas" and who concentrates the ranks of Head of Tribe and Head of Government. The Reliquum as its called, are a council of leaders from all of Hain, Human, and Roavick who speak for the people. These are selected by Sin himself, and all are members of his Cult, in secret.
What is unknown is that, since the creation of the State, the Parliament has been used as a mere facade to an authoritarian mandate. The government is almost completely centralized by the Cult of Sin. The Illumi, located at Xerxes, its capital, allocates the lands governments at its own accord, with no known election to speak of. The only elections held in Amestris is for the positions of Poloí in a tribe to join in the Reliquum, but there power is irrelevant to the decision making process. In practice, the Government is composed of nominated positions, chosen by the Illumi.
The lands tribes are directly subordinated to the Reliquum and in turn the Illumi, and have little freedom of action. However, politics are very common among the Poloí of each tribe within their own level of hierarchy, bringing a lot of competition between Tribes. All religions are tolerated in Amestris.