A city on the River Kiyaj, Opios is the largest city in its region and home to over a hundred thousand people. It is a center of commerce for the former region of Thearak, and was prior to the Moti Civil War an influential base of power in the Holy Moti Empire. It remains at present the seat of the Grandpatriarch of Iralliam who rules the city and the surrounding as an independent sovereign, and ruler of the Church State .
An ancient city, Opios first came to prominence when it became the burial place of the Prophet Kleo, founder of the Church of Iralliam and center of the Church of Iralliam under the Grand-Patriarch. Since then it has maintained a the timeless rhythm of holy city, playing host to a multitude of pilgrims (who wish to see the burial site of the Prophet Kleo) and petitioners to the Grand-Patriarch from abroad, with the city gradually becoming over time the pre-eminent center of the region. It has furthermore faced almost no threats for the entirety of its existence; resulting in a street plan is mildly confusing to visitors due to the accretion of various layers of construction over time, and enabling the city to grow unhindered by the sacking of enemy armies. This pattern of life was only briefly disturbed in the year 636 SR, when Opios was briefly besieged by an Ardavani army of the Karapeshai Exatai, fortunately the city was undamaged and the invading host was swiftly annihilated thanks to the intervention of the Kothari Exatai and the bravery of the armies of Kilar and the Church.
As of the year 930 SR the city has become one of the largest cities in the world, and the largest south of the Kotthorns in the eastern cradle, being the foremost center of religion in the Iralliamite world, and the political heart of the Church State.