One of my worlds was based inspired by Solomon Kane with a big Fae/Sidhe theme
1 Albion (England) - during the English Civil War in 1648 Oliver Cromwell first came up against a Fey-Pact Warlock in Wales. Although driven back, Cromwell survived the encounter and turned to Divine Providence for aid. Gaining the support of the Scottish Witch Finders they soon discover that those of True faith have better defence against the fey and this helps them to push back into Wales and then Ireland.
However at the seige of Clonmel a witch coven summons the Faerie Queen Melancthe, which causes the lost land of Lyonnes to rise up from the sea opening portals to the Feywild and creating a land bridge (Doggerland) across the English Channel. With the portals open all kinds of Fey and giants return to claim Lyonnes, some expanding into Ireland (which Cromwell is thus unable to subdue) and others heading to other parts of the world.
The Lord Protector squirms as Old Shuck once more terrorizes the moors and goblins infest the sewers of Manchester. Cromwell does claim Doggerland and looks to Belgium and the other Low Countries to form a broader Protestant alliance against the fae. Robert Cromwell becomes the Second Lord Protector of the Commonwealth a Puritan tyrant following in the footsteps of his father to ruthlessly enforce the law against scorcery in the regions of Albion and Doggerland.
As Fey and Witch-finder forces clash in the Protectorate Lands, Witches and lesser beings flee into Europe.
2 In southern Europe the Grand Inquisitor Torquemada has risen to become the Primus of the High Church and pushing up to claim France for the Church declares a holy war begins a campaign of genocide against all non-human races and those he declares in league with Hellspawn. At the same time Candida Torquemada former wife of Torquemada whom he had imprisoned in an Monastery due to her insanity takes over the asylum and makes a pack with the Hellspawn Nemesis by whom she has birthed two hellspawn children Barbossa and Murcalla
3 Central Europe/Black Forest was inspired by Fairytales so think Disneys version of Snow White or Beauty and the Beast, and of course the darker sexier versions of Red Riding Hood and the Werewolf
4 beyond the Carpathians Rugeivit The Howler, a Lycanthrope Warlord of the Western Slavs musters his forces, vying against the Vampire Boyars, offering a refuge to those accused of witchcraft and dealing with Baba Yaga and the other old gods who begin to stir.
5 Further south Amcazade Pasha Grand Vizier of the Ottoman Technocrats leads clockwork armies, flying carpets and griffins to occupy the Balkans and menace Venice.
6. In Afrika, Egypt has faded but the Sahel is prominent due to the fabulous wealth of Timbuktu, Mali, Tu-Anziko*, Gondar and further south the Towers of Great Zimbabwe are still occupied.(I took lots of inspiration from the Epic of Sundiata Keita)
* Tu-Anziko was my fantasy African kingdom, inspired by Burroughs/Phillip Jose Farmers “Ancient Opar” (ie the Congo Basin is an Inland Sea)
7 India I mainly focussed on the Mughals but didnt develop it much further and Khitai was set during thre 3 Kingdoms period.
8 The Naga-Khmer and Champa occupy SE Asia and Majahapit Empire across Malay and Indonesia.
9 I’ve got an entire Polynesian campaign (Legends of Hawaiki) based on Polynesian myth
10 Also had Bucaneers and Voodoo in the Carribean, whereas South America (An-Huacan) was a contient island dominated by Maztica and seperate from Tolton (a narrow island that replaced North America but was far smaller until it merged with the Arctic)