The central setting, primarily encompassing a continent of indeterminate size and ocean of similar dimensions, of The Passing of Blades has no defined name, and as such is often simply referred to by its residents as 'The World'. The World has seen many nations rise and fall, as well as three successive empires over the course of The Modern Era.
The Eladrin Empire which is the most recent of the empires, ruled by the eponymous Eladrin who crossed over from The Feywild and wrested control of The World from the Tieflings. Their dominion stretches from the western 'light-house' of Neverwinter all the way to the eastern border known as The Ashen Reach.
Bael-Turath which was lead by the Tiefling race, first forged from a pact between an ambitious group of Humans and the Archdevil Asmodeus. While reviled in their roles as antagonists against the imperial crusaders of the Eladrin, their rule marked a notable period of relative peace, arguably due to the power afforded to them by their infernal patrons. Small remnants can still be found in the eastern territory of The Eladrin Empire.
The Arkhosian Empire which was the first and most enigmatic of the three empires, founded by the Dragonborn. While evidence exists in the form of oral traditions from those Human tribes that were in contact with the empire and the strangely few ruins that such an empire exists, the sudden disappearance of the Dragonborn themselves leaves the true nature of the empire a mystery to most.
The Free City was originally a small settlement built around The University which soon grew into a thriving metropolis comprised of merchants, imperial outcasts, and those that had nowhere else to go. With the backing of the world's most powerful mages, The Free City has stood tall against the changing tides of the fall of Bael-Turath and the rise of the Eladrin Empire, maintaining strict independence all the while. It is said that the influence and strength of The Free City is the primary force that keeps the Eladrin Empire from attempting to expand eastward.
The Scarlet Principalities are the subterranean nations headed by the six Dwarf princes who are said to represent the six 'quadrants' of The World. Isolationist and xenophobic to a fault, the only true interactions they have with the wider-world are limited trade with a select few merchant clans. Despite this callous attitude, Dwarven art and technology is highly coveted by surface cultures, leading to a thriving black-market that deals in such goods. Rumours also say that the true power behind The Scarlet Principalities are the elemental Outsiders known as Genies, though such reports have never been confirmed.
The Nesting Sea is an unofficial fiefdom mainly populated by a mix of Elf and Human sailors, generally ascribed as being part of the Eladrin Empire, though the boat-cities themselves act as autonomous entities. The growing importance of naval trade between cities on the Eladrin Empire's coast and other independent kingdoms lower on the coast has led to the Elves becoming seen as the foremost merchants of the age, much to the chagrin of their Fey cousins.
Shrykediell is a fledgling nation based within the western center of The Eladrin Empire, founded by Kenku nationalists who claim an ancestral heritage to the land. While not officially recognized by any major power, it has so-far managed to repel attempts by the Eladrin to reclaim the territory owing to a mix of guerilla warfare and the Eladrin's underestimation of the Kenku's regional popularity.
As a final note, it should be said that the Human race's cultural propensity for a more nomadic lifestyle has lead to a lack of sizably established nations. However, this has also lead to Humans often becoming the largest minority in most nations, having learned to adapt themselves to the local norms, outside of exceptions such as The Scarlet Principalities. The more druidic Orc and Halfling kin, as races more attuned to the natural world, have no permanent settlements, living alongside nature rather than shaping it to their wills.