The Inquisition was founded in the late 100s based in the Duchy of Alrhone, mostly focused on the city of Oschich, their main base of operations. The Inquisition is the most powerful military force in the Kingdom of Ravenna, with very few warlords even pretending to be equals in force. The Inquisition is technically independent of Ravenna, though there are several pieces of legislation left over from the old days tying the Inquisition to Ravenna during times of need or crisis. The Inquisition makes its money off of selling crops grown in their territory and taxing peasants that live in Inquisiton land.
The Inquisition is led by a State Court, which is led by the different organizational heads in the Inquisition, and handles organizational issues, while lesser matters are delegated to the General Assembly, made up of the different Justiciars inside the Inquisition, both inside the officially relegated territory and outside, serving abroad. Below that, the Inquisition is split into two branches, the Men-At-Arms (or the Lawmen as they're more commonly called), and the Chancery, the administrative branch of the Inquisition. The Lawmen mostly consist of volunteers as a core force, though peasant levies and mercenaries are hired frequently to serve as a supplementary force to the main military. They're moderately well armed, with a set of standard gear like a helmet and chainmail. The amount of gear a man-at-arms are allowed to wear is strictly budgeted, and if they are in possession of an above average amount of armor, then it will most likely be confiscated, and the offender punished.
The Chancery, despite not being very public in their appearance, makes the Inquisition go round. They write the reports, the writs and the different acts and explanations. However, this branch of the Inquisition, as a byproduct of the values of the organization, is extremely bloated. Most reports aren't read, and are instead filed away in one of the grand libraries of useless papers in Oschich.
The Inquisition was founded in the late 100s, when Ravenna was undergoing a bit of a crisis. The Dozmi bandit gang and the growing crime problems continued to threaten the young nation, and the royal crown was unable to respond because of a lack of authority by the central government, and the uncooperative army. They were in need of a new organization, and they begged the Duke of Alrhone, the most powerful of the nobles, to help out. Taking full advantage of the weakness, the Duke raised his army, and proceeded to decisively defeat the Dozmi bandits in multiple devastating engagements, all while squeezing anything he could get out of the central government, until the Duchy of Alrhone was basically its own nation.
The Duke then declared that his duchy was the Inquisition, and was subject to special consideration from the crown. Since the Kingdom was so reliant on the Inquisition to clean up the mess currently taking place, they simply rolled over and accepted it. The Inquisition did solve a number of problems, like destroying multiple infamous bandit gangs that terrorized the countryside, occupying multiple crime-infested Ravennan cities to bring them under order, and starting a bloody purge of the government with permission from the King, mostly solving corruption by scaring everyone who was corrupt into not being corrupt for a short time period out of fear that the Inquisition would find them and then execute them.
After the crises were over, and the Kingdom mostly preserved, the Inquisition, rather than being dissolved, decided to stick around and declare their independence from Ravenna, only connected to the country through a few pieces of legislation that allowed the head of state to call upon them in times of need. Since then, the Inquisition has maintained their strong military and territory, maintaining it against the warlords that roam Ravenna. The Inquisition has almost never been called upon in its history to combat, except in the case of Darshi Yaun and her crusade to unite Ravenna.