Kirinal Concordance Zone
The eight most powerful armies in the world with their weapons pointed at a 30-mile hole in the ground. It's a powder keg. We're the match.
The might of one nation could not halt the unending march of invasions from a hole in reality. Traditional enemies: human, orc, elf, drow, dwarf, and goblin; had to come together to prevent their world from falling to the Far Realm or becoming a sacrifice in the Blood War.
Under the Treaty of the Concordance for Survival, The Kirinal Pit and the lands for 20 miles around it are a neutral zone administrated by the Concordance. The Concordance Zone is split into eight cantons, city-states run by members of the Concordance.
They coordinate on defense and military responses to threats from the Pit. They are completely independent on internal matters and trade.
Almost no one calls them "cantons" they are referred to as the slices of the pie.
The Eight Cantons
Eight cantons. Eight fortresses. Eight armies.
A Pit Wall was built directly on the edge of the Pit and fortresses were built at the cardinal and ordinal points around it. Towns grew up to service each of the fortresses and for defensive reasons they were built five miles away from the fortress they served. This gave the residents of the city enough time to shelter in place, or flee, if conditions at the Wall became especially bad.
These towns were originally called the "Embassy Cities" because they represented the members of the nations and organizations who were members of the Concordance. Despite the lofty title, for the first decades of their existence, they were just small trading towns. No one wanted to live close to the chaos coming out of the Pit. Getting assigned to an Embassy City was seen as a punishment.
That changed with the completion of the Orrery of Worlds in 3100 FA and the establishment of the Days of the Week. It started with the establishment of interdimensional trade with Faerie and some of the Elemental Courts. The practice of salvaging dead civilizations and harvesting resources from other worlds became possible. People made pilgrimages to the Zone to visit Heaven.
Suddenly the cities of the Zone began to grow and becoming great cities and even metropolises.