The Countries:
For years the countries of Agira, Xananand, and New Terus had been on good terms with each other. Agria and Xananand each had alliances with New Terus however never with one another, and realative peace had fallen over the continent. As time wore on the relationship between Agria and Xananand slowly became more and more strained. Xananand was terrified of it's larger neighbor, while Agria became increasingly paranoid about them. The increasing stress on the relationships between the nations fuled a scramble for new military technologies. New Terus warned it's neighbors against such brash actions, but they did not listen. Agria came on the scene first with their early fire arms. Once they had been discovered the military took the weapons under their wing and taught everyone how to use them. It was noted that although fantastic and powerful, the weapons did little to sway the tide of a fight one way or the other against opponents that did not possess firearms, but it was a small advantage that Agria could laud over it's neighbors with. Soon New Terus spoke of a new technology, but never unveiled it to either Agria nor Xananand, and hearsay says that the small nation never really had anything. Xananand was all that was left, and they more than made up for the wait.
The Coming of Magic:
Magic had always been around, but it was never something humans, or demi-humans for that matter, had any control over. No, it was a much more primal concept. A few rouge elementals here, a couple undead there; once in a while, assuming they were very lucky, a god would bestow somebody with a small amount of divine power, but as a whole controlled magic was rare, and Arcane magic was unheard of - until Xananand found it. No one really knows how, or why, or who did it, but everyone recognizes that Xananand did it first. It was around 50 years ago that there was an explosion of blue light from the direction of Xananand. Anyone who was outside saw it, even if it was just a slight flash. The next week saw a courier from New Terus running as fast as he could to the capital of Agria, Rayne. The leader of Agria, Lord Valle, received him, and shortly after announced that it's neighbor to the South West was under attack by Xananand, who had control over the arcane forces of the world. Something like this was insane, and most of Agria believes that Xananand did this not as a plan to conquer New Terus, so much as a show of force to their perceived enemy. Lord Valle gathered together the most politically powerful, the wisest, and the richest members of the land and set to work on a plan to protect Agria.
The Wall:
No one remembers that The Wall once had a more proper name, everyone just calls it as it is; The Wall. The Wall surrounds the western front of Agria in 3 stages, each section between walls is about 2 miles wide, and packed with military shelters, civilian populace, shops, banks, and everything else they could need. Originally only military was allowed between the sections of The Wall, however the costs of building the monstrosity were so taxing that the toll to get through it is impossibly high for some. However, refugees needed a place to stay, and so the Boarder Towns formed, and the military does it's best to keep the peaces and protect it's countrymen. The Wall stands around 100m tall and is composed entirely of metal. To the general glee of Agria it was completed in 30 years time and had only strained the economy to the point BEFORE collapse. So Agria was safe, or so it though.
The ADMIN:
The Agrian Department of Magicical INvestigation , or ADMIN, was founded 15 years ago. Although Agria had created The Wall, and housed within it multiple military personnel and law enforcement, no one had the training to deal with crimes, attacks, etc. of a magical nature. Thus ADMIN was created with the go ahead of Lord Valle and his associates. ADMIN trains recruits to hunt down, investigate, and cease all forms of magical crime and terrorism. This includes the use of those with the ability to use magic, with a specialized permit and extensive training and evaluations. Anything to do with magic is sent through ADMIN and they dispatch a team in order to clean up the mess and restore order to it's rightful place. ADMIN keeps to themselves and has grown into almost a third party. Although they are patriotic and associated themselves with Agria, they are contracted out, not ordered per-se. The main ADMIN branch is within the capital of Agria, and each section of the wall also houses an ADMIN hall somewhere within it. To the public's knowledge no one ever leaves ADMIN once they are in. ADMIN is headed by Commander Johannas Mercy, few people honestly know what he looks like or who he is, but no one ever wants to meet him.
Your characters are part of ADMIN and have just finished your training. you have a little bit of experience under your belt, but not much. As part of the training you have all finished at least 1 case with a Senior Officer, but if you've done much else beyond that is up to you.
As a Note:
yes there are more countries in the world than just 3, however these are the 3 countries on your continent.
If you have any more questions concerning the background of the world just post them in the discussion thread and I will respond both on this and in the thread.