Dise is a major pre-war city in the pre-war nation of Caledonia.
During the War
Dise was a city that had a heavy focus on gambling. The city also had the patronage of Wallkirk, Mr. House and other wealthy/intelligent ponies. The city itself had a series of tunnels built to be radiation resistant, but the materials used were not effective, making them nothing more than a web way of tunnels. The city had several major casinos, including Mr. House's personal casino, the Black Salamander.
Much of the city survived the war, ponies like House survived as ghouls and would work to rebuild the city. The city has a constant influx of travelers, immigrants and traders from the rest of Caledonia and from Equestria itself. Due to the efforts to rebuild and the state of the relatively intact city, it earned the title of the 'Last Great City'. The city has an outer region where most of the arriving ponies who can't pay the toll live. Past that is the city itself which includes a compound run by the Watchers, three casino's run by three powerful gangs and the city's water purification plant.
The inner city has a fenced off area where Mr.House's casino the Black Salamander sits and an NCA embassy is also present. The inner city has much better protection and everyday luxuries. The tunnels below Dise are populated by groups of ponies and an orphanage was set up by a pair of alicorns, who teach young orphan foals and look after them.
Dise has several factions vying for control or power. Some of these factions are in direct or indirect conflict with one another.
The Watchers provide free medical aid to the ponies of Dise and are the most experienced doctors in the city. They help anyone who comes to them for help, regardless of their affiliations with other factions.
The Hizais are Mr. House's personal army, representatives, agents. The Hizais are all cybernetic in some fashion, ranging from elaborate full-body cybernetics, to cybernetic limbs or cybereye/ocular implants. They perform numerous missions for House, all across Dise and Caledonia.
The Mustangs are a gang who run The Moon casino and also control the water purification plant. They are the only people with knowledge on how to run the plant. Their leader, Roy Mustang was killed when the Maizes tried to capture him, The Mustang's survived and repelled the invading Maizes.
The Galicians are run by the elderly Granny Dynamite. She is a wise and experienced gang leader who also has command of numerous Ponitron robots.
The Baises are run by the Mule, Molly. The Baises are a gang looking to expand their influence over Dise. They control the underground fighting ring, hosting gladiatorial battles.
The Finishers are a smaller gang that are looking to replace the Maizes or Mustangs. Though not as powerful as the bigger gangs, they still have considerable influence and ties to factions, like the Enclave Remnants.
The Enclave Remnants are a group of pegasi, descended from Pegasi who seceded from the Enclave. They took their equipment when they left, including power armor, energy weapons and vertibuck cloudships. They hire out their services in Dise as mercenaries, bodyguards etc. They were also involved in a war with the local Steel Rangers.
The New Caledonian Alliance (NCA) are a large faction of ponies, controlling several settlements across Caledonia. They have an embassy in Dise, though they do not control the city. They do run the outer checkpoints for entering Dise.