What is the campaign setting? What world is the campaign set in?
An alternative fantasy version of historical Earth.
Imagine the Earth, your Earth, in ancient times, in medieval times. But it isn’t your Earth. No, it isn’t your Earth at all.
It is similar to your Earth in that ancient Rome exists, as does Greece. Sparta, Athens, Macedonia, they are all there.
The Gauls span Europe but the dark-age Franks rule Frankland while Aragon, Castille, and Granada constitute medieval Spain.
In Briton, the Celts control the remote highlands of Wales (Cymru) and Scotland (Pictland) but Arthurian Britons control Angleland. Ireland is two islands not one, and they are larger. But they are all Celt.
Iceland (known as Stelland) is Norse, as is Greenland (Albornia), and stretching across the lands of Scandinavia are the Saxons and Danes.
To the east of the Hellenes, one comes across the Persian Empire, but here the known maps begin to change. The Persians are based out of Troy and their Empire extends around the Black Sea to Armenia but also to the north to the mighty Serpentine Mountains which run from the Inner Seas to Spain.
North of the Mighty Serpentines are the lands of the Scythian Horse-Lords and the Slavs.
The geography to the east is very different and contains the arid lands of the Bablyonians, the Sumerians, the Phoenicians, and the Assyrians.
South is the Nafad Desert and numerous Arabic Sultanates.
Ancient Egypt exists as does it neighbours, Punt and Kush.
The shape of the continent of Africa (called Ghana) looks similar but a closer look reveals substantial differences. Many of the ancient nations exist (Ashanti, Masai, Zulu, etc.) but the landscape is very different.
A large desert (the Ankh Desert) consumes the north and here can be found some familiar nations (Libya, Carthage) but also some unfamiliar ones (the Red Glaze nations with a similar culture to Carthage).
The eastern side of the continent is dominated by a massive Jungle and populated by Indian peoples (Khalistan, Hindustan, Islamastan).
The south has been conquered by a pale-skinned northern people who call themselves Abyssinians. Their culture resembles medieval Germany (or Warhammer’s Empire).
Across a narrow sea to the east can be found the continent of Quistom (Australia). Now this continent has no similarities with your Earth but instead is home to dense, lush forests in the north which house the largest Elven Realm (The Anoraranian Elves or Sun Elves).
The middle of the continent contains a massive mountain range and beneath them live the Dwarves of the Deep Realms (from Forgotten Realms).
Along the southern coasts dwell the hillfolk, the Gnomes of Glittlerand.
Only the western portion of the continent contain humans and here we find Bablyonian peoples who have migrated southeastward to establish a number of kingdoms that together are known as the Babylonian Federated States of Quistom (BFSQ).
The Scattered Sea Islands that fill the waters to the north of Quistom are home to more Indian nations.
But north of the Scattered Seas the geography bears no similarities to your Earth but instead provides a desert continent that is home to many Arabic Sultanates and Caliphates in the south but shifting to hills and mountains, and Mongols to the north.
Across the eastern seas lies Japan in all its Shogonate glory.
What lies east of Japan is only myth, legend, and conjecture. There is no knowledge as to the size of the Earth. The most knowledgeable about these matters claim that the continent of Middle Earth, 400 years into the Fourth Age and after the destruction of the One Ring, lies far, far to the east, beyond all maps and known travel routes. But access is blocked by The Great Rift, a sea of endless blackness that consumes all who enter. The origins of the Rift are unknown but clues and hints lie in the mythologies of both “worlds”.
To the far northwest is the continent of Balston (North America). Here we find a geography that has many similarities but also many differences. The First Nations (Haida, Anishinabe, Dakota, Apache, etc.) are spread across the continent but so too are Norse Clans (Nordheim) that have migrated from the northeast and are in a constant state of war with the Indigenous peoples.
To the south are dense, lush forests and again, we come across another group of Elven Kanons who belong to the same Realm we encountered in Quistom.
South of these rain forests can be found the lands of the ancient Aztec, Mayans, and Incans.
But the entire continent of South America has been replaced with Hyboria (Conan’s world). The map is almost exactly the same and contains all the same nations (Cimmeria, Aquilonia, Turan, Stygia, etc.)
But the peoples mentioned thus far constitute the Good Kingdoms (for the most part), the Servants of Light, the Southern Nations. Where lies Evil then? Evil can assuredly be found everywhere but one of its primary sources can be found deep under the Earth, in the Underdark, in the cities of the Dark Elves (the Drow from Forgotten Realms), such as Menzoberranzan.
But look also to the North. The most northerly sections of the world maps contain a territory that spans from east to west and is known as “The Burned Lands” or simply “The North”. It is said that in times past an army of prisoned demons were unleashed from Hell to wreak havoc upon the Earth. And their fiery path as they moved from east to west left a barren, frozen wasteland. The North is home to the Servants of the Shadow: Goblins, Hobgoblins, and Orcs, Trolls, Ogres, and Giants, Skaven, Beastmen, and Draconians, Bugbears, Sahuagins, Gnolls, and Kobalds.