Human cultures, roughly from the time around 1000 AD were summoned into a fantastic world where they started to colonize the new world, bringing their traditional cultures and customs with them and establishing the Realms of Ashkardia in a strange and exotic world. The humans were not the only creatures summoned to Ashkardia, nor did they completely replace the original inhabitants who form the base of mundane legends about fey, giants or dragons. The game combines historical real world cultures, religions and ideas from the real world middle ages with fantasy elements. The emphasis is sharply put on historical accuracy and verisimilitude. Typical elements would be the conflict of colonization, a strong verisimilitude to recreate a medieval atmosphere and thus combining exotic elements and well-known customs.

Verisimilitude
Verisimilitude is the most important trait in any fantasy setting, including internal consistency and overall believability.
Expectation towards a setting's contents is an individual and thus subjective issue. People have different interests, and different fields of knowledge. The more you know the more you expect the world to work along your knowledge.That's why you see very few low g fantasy settings around. A low g world would be not a worse choice for a fantasy setting by default, but because most people assume that anything not explicitly mentioned work just as they are used to, it would require lot of explanations and constant reminders.
Now, the more you know about a specific genre, the more refined and definitive your expectations of the matter at hand become. If you for example know a lot about submarines, actually worked on one etc. you are likely to react annoyed when you see a movie about a submarine that does inexplicitly stupid stuff. It's just the same with 'historical accuracy' - the more you know about the era and culture your game is supposedly like, the more you expect the setting to behave a long your perspective and the more often you will be disappointed, which is like a text book example of creating frustration.
If we made a survey among roleplayers about how much people actually know about the medieval era and as how important these people deem a certain authenticity, I'd wager there would be a certain correlation between the general knowledge about historical stuff and the interest of them in the game.
There is a beautiful quote by Umberto Eco about the inner logic of narratives describing this all in the accurate prose of a linguist, but I can't find it, at least in English, so I can't do much but offer a clumsy translation:
"Free imagination requires that you set limits for yourself. [...] In epic literature this limitation derives from the assumed world. This is not a question of Realism, even though it explains Realism as well: You can imagine a completely irreal world, where donkeys can fly and princesses are only awakened by kisses, but this fantastic or 'just possible' world still has to follow rules which were laid out beforehand (for example it's necessary to know if it the kiss of a prince or witch which is going to awaken the princess, or if a princess' kiss only turn toads back into princes, or, let's say armadillos as well."
That's from the addon to The Name of the Rose.
"It's fantasy" is no excuse for a lack of consistency. If anything, fantasy settings are obliged to be more accurate, and more consistent than those based on the real world. A setting based in the real world always has the usual facts, standard assumptions and the like as a comfortable bottom line to fall back on; a fantastic setting doesn't have this kind of luxury and has to establish its inner consistency and verisimilitude completely on its own. There are is therefore a much smaller tolerance area. Good fantasy takes an exotic idea and follow it through with utmost vigilance and consequence. According to Roald Dahl.
Which is probably enough name-dropping for one comment.
To put it in a nutshell, any setting rely on suspension of disbelief. You can make it easier or harder to do so by creating a framework that is more or less demanding on the player's readiness to accept the fictional world as "real" within its own merits. The harder you make this, the more you demand your players to stop thinking on the matter at hand, because any applied logic would tear giant holes in the plot and its premise, the worse the setting is.
Expanding the Background
I think that a good setting should develop out of itself, starting with a premise and following it through.
So, I tried to expand the historiacl background and add a flavored, subjective tone to the setting description.
I have also scrapped one of the original ideas of the setting - the transmogification magic - because it made the setting feeling cluttered. The basic premise of medieval cultures and fantastic creatures should suffice to create an interesting setting.
Creatures From the South
Hey there, I was just wondering, what sort of creatures did you have in mind for these aliens from the south? Something Lovecraft-ian, insectoid, inteligent but incomprehensibly different, or something else?
The creatures from the South
I thought about a crossover between many unusual little beasts. The creatures from the South bear several common traits of termites - the wandering mountains are the steadily expanding mounds of these creatures. The basic creatures were thought to be like a crossbreed between big soldier ants, naked mole rats, and star-nosed moles (also called the cthulhu mole), but roughly of the size of a big dog up to a cow. They communicate through a combination of fragrants and scents and bioluminiscent patterns they can shift over their surface.
Think of a horizontal creature with four stout hind legs and too longer and thinner front legs. While on all six, they are also very quick, and they can move backwards almost as fast as they move forward.
On its back, head, and flanks it has rigid chilatinous plates that protect its body, but on the soft belly you can see the inner organs and veins shining through the pale grey skin. The creature's head is large, and cone-shaped. It has large protuberant eyes which look almost human, and the naked, fleshless jaws feature large teeth. This maw is circled by thirteen long tentacles of a deep pink colour, which steadily move around and create the image of a sea amonia or a mane of living flesh (these are smelling organs, but can also be used for fine manipulation). When threatened, the creature can lift up its front, resting on the four hind legs and use the first leg pair as flailing arms.
They are of a pale grey to black color, but in unregular patterns, bioluminiscient stripes and dots appear on their surface.
They use items and tools to defend themselves or attack, and have a sharp, lemmony smell to them. The different items they obviously use - almost everyone wears a "belt" or "saddle" with several tools and items hanging from it - make sure, that they are not just simple animals but are able to create different tools for different tasks.
That are at least the basic creatures. Now think about what happens if they get their tentacles on transmogrification magic.