Sounds like a dream homebrew. Can you extrapolate on how you use all of this together a little more? And what do you call it when you need to name it? What map do you use? Do you have documents for your players or yourself that you can share?
I find it great for my purposes and style of DMing. I generally run modules or APs in a sandbox style in my world.
I like having lots of stuff to draw on with multiple cultures for different races and lots of history with fallen civilizations. So I like having multiple distinct setting versions of stuff to draw on so say some orcs will be Chaotic raiders of 3e, others will be lawful thug minions of AD&D, some will be druidic nature societies of Eberron, some will be Klingons, etc. with different cultures and religions and pantheons.
I have a general big picture background, so Ptolus for the theocratic henotheistic Holy Lothian Empire (fantasy Catholic Church type setup with clerics and paladins but room for polytheistic Conan pantheons as well as secondary cultural things) with Golarion for more specific countries integrated into that superstructure so the Immmortal Principality of Ustalav is a province of the Holy Lothian Empire as is Taldor and so on. Eberron has some overlaps as Ptolus has a succession war in the big empire which I like as a backdrop so the Eberron Great 100 year War at its beginning is a good parallel and Eberron has strong neat themes and elements I like to integrate and riff off of.
I think about how to weave stuff together for a neat story I like that I can pull out and riff on in game. Thrane matches the Holy Lothian Church faction, The Prince of Ustalav works well for Karrn elements, the Uncrowned Empress who was the distant heir declared apostate by the Church setting off the succession crisis can work as one of the five noble Kingdoms (Breland? Aundair?), the Imperial Steward holding the capital works as Cyre, etc. The Church is leading a crusade against the apostate Uncrowned Empress with Ustalav aiding, fighting the Kyonin province elves who have armies of living spells who supported the Uncrowned Empress's claim. I find doing syncretization fun so this works for me.
Other sources I get and enjoy can have smaller elements be integrated as I like (Midgard, Spiros Blaak, Erde, etc.) or used as background history ancient civilization things such as I do with Scarred Lands, Warhammer, and Goodman Games Known World.
It means I have solid existing world structures to draw on for my concept of the world, tailored to my tastes. I ditch things like Ptolus's and Eberron's planar cosmology that I do not really care for, and mix and match as I like.
20+ years of running games in the world and I have not needed to name it in game. I call it my Ptolus mashup setting or my mashup setting but I do not have a more specific name for it.
For a map it is mostly notional in my head. When we started in 3.0 my brother was running the Banewarrens Ptolus module set in a far future Greyhawk world with the Greyhawk gods as the Old Gods so we used the Greyhawk map with Ptolus set on the Nyr Dyv (like Greyhawk). It turned into a rotating DM shared campaign for three of us where we built off of each other's ideas for world ideas and plots when we rotated into being DM for a number of years. My brother liked Eberron stuff he was reading about the setting and added in elements of that such as integrating warforged with the Ptolus constructs from ancient history in the Banewarrens. When I started running games for other groups I kept using it and iterating on the world we had started from, as did my brother. Our worlds became much different as we developed different ideas for our different groups down to how we ran different cosmologies.
I mostly use a Golarion map as my base now with some modifications, overlaying in my head a Lothian empire and dividing stuff up into within the empire and without, and switching some stuff around like the fantasy Arabic countries to be on the West Coast like in Greyhawk, altering some of the Golarion history to match that (Cheliax going back and forth being part of Taldor or Qadira) and the Uraqi empire storyline from Ptolus (plus I threw in some history of Warhammer Chaos Dwarves turning into Scarred Lands Charduni empire, turning into Bael Turath eventually turning into Cheliax to have a nexus of evil site in Cheliax). The two big continents of Golarion I mostly keep but stuff of other continents is fairly vague, in the past I had a western one with Diamond Throne stuff and and Eastern One with Dragonlance stuff, but now I keep it a bit more vague and I am thinking of having a western fantasy Arab Dragon Kingdom thing from Midgard, but it is not set in stone.
When I have run an AP such as the Freeport Trilogy (in 3.5), or Reign of Winter (in Pathfinder 1e), or Carrion Crown or Iron Gods (in 5e), I have been able to use the maps associated with those areas straight with no problem, I just have not pulled out a full world map in game.
I usually tailor documents to the campaign I'm running and keep the focus on the more locally relevant and the more plot focused for the adventures with background information the players can use in making their characters and to get a bit of a shared world background.
Here is my world info resource I made for the players in my
pbp Freeport campaign and it is still mostly consistent with stuff I have used in successive campaigns.
