The main area of focus is a peninsula, not unlike the landmass composing Norway and Sweden, except that the "Asian" landmass is to the west, and the open ocean is to the east. On this peninsula is the country of Rasheman (pulling heavy cultural aspects from Forgotten Realms CS and Unapproachable East, including the Hathran, the nature spirits, and the Berserker Lodges). The lower 1/3 of the peninsula, which is typified by rolling hills and rather flat, arable land, has been encroached upon by an empire from the landmass to the south (much like Rome conquering the lower half of England). To fortify their landholdings, this empire has built a wall (imagine a larger version of Hadrian's Wall in England) spanning the breadth of the peninsula. The people of this empire have even twisted the knowledge of the gods, claiming that even though Balder has died, he will rise again after Ragnarok, and he will then be your only means of salvation. This perversion of the gods and the spread of the empire occurred several hundred years ago. Lots of raids and counter raids across the wall ensue...
Most of Rasheman and the countries on the surface of Midgard are exclusively human societies. There are very few half-elves and half-dwarves scattered about, together composing less than 1% of the population of Midgard’s societies. Some half-elves insinuate themselves into the society of their human parent, many never meeting another half-elf in their lifetime. Others find a connection to their elven heritage and find their true calling: they monitor the menhir circles and spirit stones that serve as prisons for demons bound in a time out of memory. These half-alfar are able to traverse the ley lines upon which these prisons have been built, passing in moments from one ancient stone prison to another, checking to ensure the rune-stones ensnaring these destructive fiends have not been disturbed. Many leaders in the human lands of Midgard also guard against disturbance of these stones, and most work willingly with the half-alfar in their task. The alfar themselves rarely visit Midgard, though half-alfar will sometimes visit Alfheim by following ley lines to the menhirs in that forested realm.
The half-dwarves of Midgard are almost exclusively reclusive, and they gather into communities far removed from human lands, either in mountains and caves, or beneath Midgard itself, closer to their parent’s world of Nidavellir. True dwarves visit the deep places of Midgard quite regularly, traversing the tunnels connecting Nidavellir to Midgard in search of precious metals for use in their magical crafts. Some foolhardy individuals seek out the greedy and vindictive dwarves for their innate magical crafting abilities; abilities which rival the greatest crafts of the most legendary sages lost to memory but for the tales of the skalds.
In the mountainous highlands of northern Rasheman live only the heartiest of men. They are a very superstitious folk, and some claim to have seen half-giants from Jotenheim moving about in the high passes after one trapper claimed to have stumbled through a mountain passage into Jotenheim itself. The highlanders are also wary of any large predatory animals, and typically trap and ambush them quickly. It is a handy precaution, as it provides them with meat and furs for trade, and it also lessens the chances they will be taken by surprise and devoured by a Lapp wizard masquerading and hunting as an animal. They do always make non-lethal blows at first, though, for fear they have accidentally caught one of the shape-shifting wild berserkers from north west of Rasheman; the Hathran would be displeased if they killed a messenger from the Nentyarch.
People all across Rasheman and on the other side of the Ashane Sea must be wary of trolls and Huldre folk. The people of Rasheman are lucky to have the Hathran intercede on their behalf for the favor of the spirits of the land, but even the Witches can do little in the way of diplomacy with the trolls and the more vicious fey. Recently some Rashemi who went a vyking across the Ashane sea had their boat pulled under the waves by a gargantuan sea troll. There is also the ever-present threat of shape-changing vitterfolk trolls. These smaller trolls love to masquerade as children and cause mischief or lure children off into the woods.
Most of the common folk are superstitious about magic, though they may have a special talisman that can protect them in great times of need. Most people in Rasheman leave the working of runes and Seidr magic to the Hathran witches, though there are some reclusive male hedge wizards who also take up the practice. The Hathran allow these men to continue their work so long as they remain separated from the political and social affairs of their land. The oldest and wisest hedge wizards also craft a small number of talismans and other items of magic, unlike the Hathran who disdain such practices. In fact, male arcane casters are required to produce one magic item a year for the Hathran, which is collected each year at Rasheman's Althing. The Hathran then assign an item to each male arcane caster, based upon his crafting abilities, that he must have ready for the next year's Althing. If the mage does not produce it next year at the Althing, he is banished from Rasheman itself.
The land to the north and west of Rasheman is ruled by the Nentyarch, a wise Druid who has ruled that land for generations. There are few settlements of a standard human variety in that land, as most adults live among the beasts, in both proximity and form. They are a hearty, raucous people, loyal to each other, the Nentyarch, and the land, but very quick to anger, and vicious in their wrath. The few permanent settlements that exist are located in a great dale, a wide, deep valley located between a fork in the mountains. Women live here to birth, nurture, and raise their children, protected from the wild lands covering most of there homeland. But when the children have begun to reach their majority, their mothers lead them out of the valley to learn survival in the frigid mountainous forests. They join up with the males of their clan and live at peace with the beasts, and eventually they too take on the form of their animal compatriots.
Rasheman is a peninsula attached to the lands of the Nentyarch, but not at the level of the sea. In truth, one would call Rasheman an island, but for a natural bridge of wind-shaped rock a quarter mile long and half a mile above sea level. This boundary predates any history known to the Hathran, and indeed it is a powerful boundary in every sense of the word. At the center of this bridge is a powerful ley line focal point, and a large circle of menhir megaliths topped with a lintel circle was erected on the site at some time in the ancient past. Every year on the longest night in the heart of winter, the Hathran use their circle magic to help strengthen and maintain the seal this circle of menhirs forms. During this night, the protections on the spirit stones ebbs to a weak point. The Hathran posit that the stones would still hold, but they are not ones to take chances with the lives of their people. A small circle of Hathran can normally ensure the integrity of the stones, but about once in the span of each lifetime, the protections ebb to their weakest. No one living remembers a time when the stones were breached, but a myth is told of a time long ago when the stones did not hold, and creatures from Niflheim began roaming the land.
Some mechanics explanations of all this can be found
here.