Early on, the land surrounding Mount Carris was under the darkfire domain of Holz Finzi. This was not in legal terms; however, the area and the land surrounding Lake Maern was restricted from the public since 1237. Finzi subdivided the land into cantons, each run by a darkfire cartel base.
Between the 1230s and the 1250s, a long struggle ensued between the Finzi regime and the new Retunian Republic, as the Retunian government attempted to subdue a canton and compound, only to see one re-emerge again.
Also during this time arose a darkfire figure serving as Finzi's rival: Wain Berron.
Wain Berron was a roaming darkfire dealer who frequented the land surrounding Mount Carris and Lake Maern before the arrival of the young Holz Finzi in 1236. Finzi was able to master the darkfire quarry here; but Berron knew that darkfire quarries could be remastered.
On 23 October 1252, Berron attempted to overthrow Finzi and also to trigger the darkfire quarry in order to remaster it. The trigger succeeded, but Berron failed to overthrow Finzi, who had him imprisoned. After a few weeks, Finzi came to Berron and offered to release him and pardon him of his offense, with the caveat that Finzi would assign him to command the compound and canton in the Southwest Corner of Finzi's territory near Lyndonpole. Berron agreed to this.
On 22 January 1257, Mount Carris released a darkfire discharge resulting from one of Finzi's many experiments. This was not the first discharge in history but was certainly the largest thus far, sending a darkfire cloud to blanket nearly all of the town of Lyndonpole and to spread as far as North Kempton and the Basin District. With lack of knowledge at the time regarding the fundamentals of darkfire, the incident triggered panic across the nation. Between January 23 and 24, the Retunian Civil Guard launched an offensive deep into Finzi's unofficial territory surrounding Mount Carris and Lake Maern. Their agenda was to ultimately subdue the Finzi regime, but the agenda failed as RCG officers were hit with Finzi's Defensive Disorientation darkfire scripts.
However, this offensive happened in Wain Berron's canton; and on February 1, Berron retaliated by attacking and destroying RCG camps set up just outside his canton. Finzi, determining this to be going too far, ordered Berron to stop. When Berron ignored him, Finzi launched other canton forces against Berron in order to subue him. On February 2, Berron retaliated by turning his forces against Finzi and driving them toward Finzi's head compound on Mount Carris.
On February 3, the RCG launched their second offensive, during which Wain Berron was shot and killed. The RCG blamed Finzi, himself, for Berron's actions, and launched a conjoined offensive against both Finzi's and Berron's forces alike; meanwhile, Berron's forces continued to fight Finzi's forces.
Seeking to end the violence, then-Prime Minister James Black, on 4 February 1257, signed a compromise with Holz Finzi and the leadership of the Berron canton. Per the compromise, an official boundary line was drawn around the foothills of Mount Carris, with the area inside being called the Mount Carris Perimeter. And the terms were as follows: Holz Finzi, and any other person born with Involuntary Darkfire Conjuration Syndrome inside the Perimeter was forbidden to leave the Perimeter; any person born with Involuntary Darkfire Conjuration Syndrome outside the Perimeter was forbidden to enter the Perimeter; any person born without Involuntary Darkfire Conjuration Syndrome inside or outside the Perimeter was allowed to travel within and without, but had to go through a background and security check at one of the boundary checkpoints to ensure that he or she did not have any involvement with the darkfire cartels.
Initially, the boundary around the Perimeter was lined partially with barbed-wire fence near areas of relatively high traffic, but was otherwise open land. That all changed, however, when Edward Jackson became Prime Minister, who ordered the boundary reinforced with a concrete wall, the construction of which began promptly in 1261, and, when completed in the summer of 1262, stood 50 feet tall and 100 feet wide. This wall would stand until the full legalization of darkfire in 1309, after which the wall was completely demolished, with all remnants of it destroyed.
Since 1309, a simple chain link fence lined the perimeter of what is now called the Lake Maern Reserve. However, the purpose of the fence and the Reserve is to protect the darkfire community by providing a safe haven, instead of dividing and imprisoning a select demographic.