An excerpt from "On Arvum and its Peoples", a treatise by Scholar Tobias the Dubious.
Many unlearned commoners think of the Realm as covering the whole breadth of the world, but in truth it only refers to a single continent that falls under the dominion of the Compact, the continent of Arvum. Arvum itself is a vast and ancient land of diverse climes and peoples, separated into five different regions that were independent kingdoms before the forging of the Compact.
The Northlands, ruled by House Redrain from its seat of Farhaven, covers the most hazardous and difficult terrain of any of the five great houses, as many an invader has learned to their sorrow. Separated from Valardin lands by the Red Mountains in the west and from Grayson lands by the Gray Forest in the south, the cold reaches of the Northlands contains high peaks and deep valleys with few roads to make travel easy. The deep and cold reaches of the Northlands has the greatest population of Abandoned of any of the lands of the Compact, and the northern houses under House Redrain see constant bloodshed in their lands as far up as the Everwinter where no one dwells. Raised on war, the peoples of the Northlands tend to be fair of countenance but hard in spirit, but known for their lack of courtly grace and are often called barbarians- but seldom to their faces except by the spectacularly foolish.
The Oathlands in the west, long ruled by House Valardin from its seat in Sanctum, has long been called the birthplace of chivalry for Arvum, and it's true that the greatest proportion of knights hail from its reaches. Despite the extreme emphasis on knightly virtues by its noble houses, and their consistent support for the Faith of the Pantheon, they have not been the easiest neighbors for the three great houses they border. They have warred against the Northlands since time immemorial, with some blood feuds against ancestral raiders from Redrain lands still continuing to this day, and their uneasy peace with the Lyceum in the south is little better. Only House Grayson to the east have been consistent allies of House Valardin throughout the ages, but particularly in the past few hundred years when House Valardin played a key role in the restoration of the Grayson dynasty during the Crownbreaker wars. All the regions of the great houses have had such heavy intermarriage that there is enormous variety in the appearances of their peoples, but the royals of House Valardin themselves are well known for their light hair and fair coloration. Sanctum itself sits as the greatest harbor city along the western coast of Arvum, the port of call for sailors traveling the Eventide Vast.
The Crownlands, bordering all of the great houses, has long been dominated by the great city of Arx as the center of commerce and governance in the Compact. Sitting in Grayson lands (which in olden times was ruled from their ancestral home in Grayhold) Arx sits at the entry of the Gray River which connects the Bay of Thrax, leading to the Thrax dominated Mourning Isles and Saffron Chain. Grayson controls most of the coast running north and south, save a thin strip of land after the Grayforest controlled by House Redrain in the north, and past the southern Lyceum River in the south. Like the Oathlands, most of the Crownlands controlled by the houses have been cleared as farmland, but much and more of the harder to control territory such as the low hills and deep forests have fell to the Abandoned over the years since the Peace of the Queens.
The Mourning Isles and Saffron Chain, the many great isles far off the eastern coast of Arvum, have long been held by House Thrax and its vassals. In less peaceful times, reavers of House Thrax would routinely prey upon the ships of the other great houses, exerting their dominance over the eastern sea from the never-conquered seat of House Thrax, Maelstrom. Though master seafarers, the longships favored by House Thrax do not often venture far from their domain in the eastern sea, with extremely few Thraxians ever making the claim they have survived the journey to the continent of Eurus in the east or to distant Cardia in the south. The sea domain of Thrax covers the most area of any of the great houses, from the bitingly cold, wet northern reaches to the far southern tropical reaches in the Saffron Chain, so close to island city-states of the Lyceum. The Saffron Chain is often said to be exceedingly pleasant, tropical islands if one doesn't mind being ambushed by Abandoned pirates.
The warm southern reaches of the city-states of the Lyceum have indisputably the most pleasant climes of the domains of the five great houses. With its gentle passings of the seasons, warmly temperate weather, and beautiful southern coastlines and gently rolling hills, the Lyceum has been described as "the most gorgeous place in Arvum to get murdered." As famous for its dark intrigues between its rival city-states as it is for its glamorous fashion, the Lyceum has seen the title holder of Grand Duke of the Lyceum shift from house to house over its long history. Currently, House Velenosa of Lenosia rules over all of the Lyceum with talented guile, having dominion over the Lyceum from the borders with Valardin and Grayson lands to the far southern sea. Beyond the sea lays the Waste, a dead and desolate land where it is said the much distant Cardia lays beyond, of which little is known.