First is the world itself; it is thought to be dome-shaped, sitting on the palm of Renji, surrounded by a bubble of air. Outside this bubble is thought to be the element of Void (see Magic for more about Void), where only the Voidlings and Abyssal Walkers exist. The sun and two moons are simply circles of light that Renji's daughter Adthotep juggles endlessly.
Ithwan has a great many myths surrounding the past- legends of where weather comes from, what caused mountain ranges to be where they are, and also about a number of supernatural creatures; legends of short men with enormous beards who lived underground and steal human children so they could turn them into more of their own kind, grey skinned creatures that disguised themselves as old women in order to murder travellers and rob them blind. The Will-O-the-Wisp is largely similar to the legends of earth, except that instead of leading people towards danger, they are said to have helped lost travelers find their way out of swamps and dark forests without falling into danger. All these things are merely legend, however, and have never been proven to have ever existed.
Oh, some young men point to primitive tools in the black forest, or collapsed caves that bear evidence of intricate carvings on what had once been the walls and ceilings in the south east, but such are simply the ramblings of the unimportant, and not to be taken seriously.
A quick summary of Mythological creatures (please note that none of the following are considered to actually be real, and even if they where, these stories have been filtered through hundreds of years of folklore, and as such would be highly inaccurate- of course, your character wouldn't know that) Any creatures not mentioned here are probably a fairly common occurrence, or have at least been accepted as fact-
Dwarfs- Short, hairy individuals who dress in furs and soiled rags, they have foul breath and grin at all times to show off their rotted teeth. They generally live in caves. Legend has it that they are incapable of reproducing, and steal human children who stay out at night and turn them into dwarfs through black magic. Since such transformations have been proven to be impossible with current magical theory, these creatures are mostly used to frighten children.
Goblins-Stooped, wrinkled beasts with grey skin- they disguise themselves as the elderly, poor or ill and prey upon those who show weakness. This legend is one of the many reasons the gap between the rich and the poor in Ithwan is so large, and why giving alms is considered a generally stupid thing to do.
Will-O-the-Whisps- Strange floating lights normally seen in swamps and deep woodland, they are said to guide lost people to safety, skirting around quicksand, deep bogs and the territories of ferocious beasts. Even today, some people will come stumbling into a village claiming to have gotten lost and been guided out by these mysterious beings, but most often these stories come about after too much drink and are listened to with amusement, then promptly ignored.
Orcs- Green skinned humanoids. They often play the part of the 'green-man' in folktales, and are a favored form of Usis, the nature/trickster god, and third daughter of Renji.
Treants- Large, sentient trees who sometimes sleep for decades. Not often featured in legend, but is considered the favored form of Poporon, the husband of Usis.