The World Map of Nexus:

This is the world of Nexus. 100 years ago Nexus was a fairly typical D&D world. The dwarves were in their holds in the mountains. The humans were at peace in there cities, occasionally fighting off the undead when needed. The elves were, as ever, in their great and ancient woods studying the nature of life. The Peoples of Boroshinkai waged endless battles both internal and external for pride, honor and peace. One hundred years ago there was great cataclysm. Six pillars of seemingly divine energy struck the lands and split powerful magic into the world.

There are 6 gates in Nexus, each associated with one of the inner planes (Though knowledge of the planes is scarce and known to few but the most dedicated researchers). Earth, Air, Water, Fire, Positive Energy, Negative Energy. These gates appear as huge pillars of colored light reaching up into the sky. Most of these Gates have a major city centered around them, commonly called a gate city. I'll briefly describe all the gate cities and their current and recent history.

Earth (Bella La Nai):

Bella La Nai is the Capitol city of the Moon elves. It is the only break in the canopy of the Skyshroud forest and the moonelves believe this is what makes them different from the wild elves and wood elves who inhabit the rest of the forest. Before the coming of the Earth Gate the elves of this region worshipped nature and had mostly forgotten about arcane magic. The Sun Elves of Port La Sali, however, had kept strong in the Elven tradition of arcane study.

When the Earth Gate came it's base landed in the middle of a giant oak. Shortly after the Oak began to change. It and all the trees around it were enriched and grew to twice their size. The Earth Gate tree it self was over 400 ft tall and 50 ft across. The Elven druids were fascinated and a new excitement was felt throughout the Elven city. Magical research on the gate began, both Divine and Arcane. A new order of clergy worship the tree as a god, for it awoke when the gate struck it. Some elves believe that the tree is the gate while other believe it only speaks for it. Some Wood Elves and even Wild Elves ventured to the capitol to see the tree with their own eyes and in some cases pay homage.

Air (Wind Stone):

Wind Stone is near the former capitol that the dwarves held in the mountains. The Air gate fell only a few miles away from their great hall.

Through there excavation the dwarves discovered a huge deposit of light metal which they first mistook for mythryl. After the discovery of stones that "fell up" when dropped the dwarven clergy and mages realized what had happened. The elemental gate had infused the ore around the gate and in some cases made it lighter than air.

What followed could be described as nothing less than an industrial revolution. The dwarves first created simple floating sleds using the new ore whish they called 'floatstone' to help them in it's extraction. Through there skill, advanced craftsmanship and through a bit of arcane magic they developed there rudimentary steam technology into the first mobile engines. Trade in fine armor and weapons made from the floating ore caused a boom in the economy of hte dwarves. They became the most well off country in all the globe.

The creation of the first airships came about 50 years later, this was after a discovery of particularly strongly infused floatstone. Refining techology along side engine design advances has caused progressively faster and more maneuverable ships to be created.

The Dwarven Empire has a standing air force, and a few ships operating an air bus service from the capitol to Tolaria, St. Micheal's Keep or Bella La Nai. It is a strict law of the empire that law airships are property of the dwarven kingdom and that they never be sold to a third party.

Fire (Boroshinkai):

This is your typical Rokugani type oriental adventures setting. I've not put too much thought into it so far so I'll just say that there are samurai, monks and wizards here. They fight a group of demons endlessly (the fortress of the nameless one).

The people of this country also pay Homage to a Phoenix which lives in the volcano that the fire gate is situated on. The Pheonix rarely leaves it's volcano but is sometimes sighted flying from it's nest in the volcano for short trips.

More coming on Boroshinkai and Ikaran soon.

Water (Tolaria):

Tolaria is a City Run by Wizards for wizards. It has a major school of magic dedicated to every arcane school, as well as a research center for the planes.

The island it self floats about 500 ft above the surface of the ocean and below is a city on floats called Porttown. It's a home to traders, pirates, fisher men and privateers. Both are center around the water gate. The Island is kept where it is by means of a spell which harnesses the power of the gate, causing it to be pushed up by the water.

If you want to be a mage doing arcane research this is the place to be.

Negative (Fortress of the Nemesis):

Nothing is known about this place other than it is the keep of a great and powerful necromancer which likes to make his presence known to St. Micheal as often as possible. When the gate came the necromancer grew in power unimaginably.

Plains of the Dead:

This is the site of countless battles between the Kingdom of St. Micheal and the undead armies of the nemesis. Ghosts of falling heroes, lost souls and the beasts which feed on them are common in this area. Many a budding necromancer venture here to conduct research and test their mettle against the undead.

Positive (St. Micheal's Keep):

A human city of peasants, clergy, paladins and fighters. The King is a paladin of some esteem. They make war on the Nemesis.

The Screaming Cloud:

So named due to the hideous shrieks and wails that come from this black mass of swirling purple and black cloud. Nearly nothing is known about this cloud other than it is the size of an island and has never dissipated. All attempts to approach the could and learn more of it's nature have been greeted by a swift lightening bolt or a sudden change of wind causing any airship to be blown off course. The cloud is too high off the ground to be reached from the sea. All efforts of the Tolarian researchers to scry on the inside of the cloud have turned up null. The could is located in the middle of the southern ocean off the coasts of all four major cotenants. There are many rumors as to the nature or origins of the cloud but no solid facts. All expeditions to learn more about it have ended in failure, though none of have been slain by the clouds apparent defenses. Many believe that the cloud is an evil god biding it's time.

More on the gates in general:

    Magic in the world: Magic had been almost entirely forgotten before the coming of the gates. Clerics could still heal and turn the undead but there powers were limited. It was as if the world lost it's magic. The wizards had become more historians than wielders of arcane power. The gates re-infused  Now Clerics draw there energy and spells directly from the gates. Some worship the Idol of the gate while other pray to the gate itself. Both producing the same effect. Wizards were overjoyed by the coming of the gates as it provided them with a source of mana to draw on. There spells regained there potency and they could once again casts more powerful spells.

The official word on Knowledge (the plains):

Since you guys are all so horny about the plains and everybody from turnip farmer to arch-mage seems to want to take this skill. I will put down the official word with respect to how many ranks of it you have.

1 rank: A plain is like another world only it has different properties from our own. There are 6 elemental plains, which correspond to the six gates that have crashed their asses into the world of Nexus. These forces are what the world is composed of; There have never been and never will be any other plains.

2-5 ranks: The gates can be used as portals to their according plain but for some reason people don't do it. You have no idea how they would anyway and wonder why people don't just jump in. There is a rumor that once upon a time there where other plains. This is likely the delusion of mad wizards and old fisherman telling tales.

6-7 ranks: There are tomes which describe other worlds and magiks which could be used to get to them, however, due to the large number of fake tomes circulating among peddlers and traveling merchants, it has been dismissed as fancy of a mage worshipping subculture. There is an elemental plane of Shadow and an Ethereal plane which coexist with this one (The prime material plane) and magic which can manipulate it is nearly within the grasp of some of the more powerful Clergy and Magi.

8-10 ranks: Teleportation is a newly rediscovered form of magic. It is incredibly difficult due to the highly complicated spells themselves. Teleportation and any other form of extra-planer travel seem more difficult then they are described in the Eldritch tomes and ancient holy scrolls. Summoning spells seem to be in a similar way. None of this has sparked serious investigation in the magical community as it is simply assumed that these are especially difficult tasks to perform. Also as the result of various experiments it seems that summoning can only be performed on creatures currently living at some place in the material plane of Nexus. There is an allusion to other planes made in the tomes on Conjuration but none of the spells given will work, they have all been modified to conjure from Nexus..

11 ranks: I'll tell you when you're older kids.

20 ranks: An intricate knowledge of the history of the gates, their origin, etc. In short, the entire truth about the history of the gates. (Don't feel burned, nobody knows this but the DM and some of it he's not even sure of, I mean of course he knows everything and that which he doens't he will quickly make up on the spot!)