In the northern forests live a secretive race of beings known as the Uldra. These are not dissimilar to the gnomes of other worlds, but have many of their own characteristics. They are described in detail in Dragon magazine #119. Their cavalry ride reindeer.
Elves of the Middle Sea world either live mostly solitary lives (or in very small groups), or else a nomadic existence similar to Romanies in our world. The main exceptions to this are the three Faerie Courts.
Half-elves are pretty much what it says on the package.
Dwarves of the Middle Sea world are sometimes called "Machine Elves". They delve deep into the mountains, and say that they have a vast underground kingdom, where dwarves tend the World Machine. Perhaps this is true, but no one else has ever seen this World Machine, and the dwarves are not very forthcoming about what, exactly, it does. It doesn't help that all dwarves on the surface are self-admitted "deviants". No one, except possibly the dwarves themselves, is quite sure what that means, and the dwarves get quiet when pressed on that point.
"Half-Orcs" represent the more human-like ape-men. They cannot actually interbreed with humans.
There are no gnomes or halflings in the Middle Sea world, but see Bunrabs and Uldra above. Also, none of the various subraces of elves or dwarves exist, at least as player types.
There is a single kingdom, located on the eastern side of the mountains, that knows the secrets of building airships. These ships are expensive, though, and so there are not many of them. There are two sorts, airships with aerial sails, and airships with hand-cranked airscrews.
Sample airship, airscrew type: 40 turncranks, 1 captain-pilot, 1 pilot, 6 officers, 2 carpenters, 2 foremen (that is two shifts, allowing the vehicle to keep going 16 hours per day). Normal speed: 5mph (15"). Capable of bursts up to 20mph (60") for up to 15 melee rounds by tapping the flywheel, then requires 30 minutes at normal speed (or 15 minutes at a stop) to recharge 1 melee round worth of burst speed. Cargo, etc: 20 tons/40,000 pounds (can be used for artillery, troops, extra crew for artillerists and such, provisions, and so forth as well as cargo). Cost: 710,000gp (most of the cost is enchanting the hull so that it can levitate). The airship has 12-72 structure points. They normally mount several cannons on the upper deck, generally at least one facing in each of the four directions, that can be depressed or elevated to hit targets up to 45° off of horizontal.
I don't know what lies to the west, across the ocean. I've been looking to make some saltbox rules that would allow the players to discover that, if that's what they wanted to do.
I don't know what lies to the east, past the Wardoms of the Ablash Isle. Same situation.
The far south eventually leads to a realm of fire and volcanoes. The far north leads to an endless track of snowy wastes. Or so it is said.
For a while, I thought that the Middle Sea world was a small part of a giant ringworld or dyson sphere, but I now know that isn't the case (that would be a pretty neat environment, though; maybe someday, in another campaign).
I don't know who lives in the huge canyon just to the northwest of the sorcerer-kings' lands, but I do know that there is a trade route that passes through there and crosses the desert beyond. Are there bandit kings in that canyon? Possibly. I suspect, though, that it is mostly bands of ape-men.
In the sorcerer-king city-state of Morda, which I'd mentioned previously as being ruled by a necromancer-king, slavery is illegal. Such menial labor is performed by zombies and skeletons. Any slave entering the gates of Morda is immediately made a freeman on request and provided with a small stake to begin a new life. Slaveowners, of course, simply do not bring their slaves within the gates of Morda. However, the occasional escaped slave makes it to the gates and is granted asylum. It may be hazardous for such freed slaves to leave the Mordim lands, however.
Strange froglike beings known as Skwugs live in the marshes along the south edge of the Dead Lake (where the Kindred of Juiblex have their fortress). This is a colony of the main Skwug marshes along the edge of the Salt Sea in the Murai lands, however. How they crossed the desert, and how they maintain communication with their homeland (if they do), is unknown.