Hello,

Im curious if this sounds like a good premise to start with (or if it feels convoluted)

• A Fantasy/Steam Punk world that has never been fully mapped due to the worlds immensity...a world so large (think of the size of Jupiter)
• Time line that has no certain reference of its creation, rather no one really knows how old (or few creatures really know) the planet is.
  

I know it's fantasy and all, but if you have a terrestrial planet the size of Jupiter, there's going to be some gravity problems.

Realistically though, that's not the only reason why the place might not have been entirely mapped. Most civilizations weren't able to cross large oceans until well after the year 1000 AD. Depending on where your story is being told, they might just not have explored many parts of the world. Some places like Antarctica couldn't be safely explored until quite recently due to its hostile environment.

The timeline part sounds fair to me. That's basically how things were for us in real life until quite recently (and even then we only know history until a few thousand years ago, anything past that is scientific speculation). I always found it odd that so many fantasy worlds had a four billion year old dragon or such that was there from the beginning (or a few thousand years if your planet was made by the gods, as seems archetypal of fantasy).

Other thoughts I've had about this world:

• Technology varies greatly from place to place
• Technology has more of an archaic medieval techie feel (steam punkish)
• Divinity has its place in the world, in some parts exclusively and in some parts void
• Magic is rare and reserved to few known parts of the known world.
• Kingdoms are volatile and only few remain over x years during the age of which the story takes place.
  What do you guys think of the foundation so far?
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  That mostly sounds fine to me. Technology varying from place to place is quite realistic. After all, compare the European explorers to the native Americans. The choice of a steam punk styled medieval world isn't unreasonable, but the details are a bit lacking here. If they have steam powered robots but no guns, for example, I'm going to be confused.
  
  
  Divinity and magic seem to vary tremendously among fantasy worlds, so do whatever sounds most interesting to you. I would wonder why magic is rare though. Too many fantasy stories have it so that magic is an in born trait, which makes it feel cheap to me. I like people to work for what they have. Of course, all up to you. Divinity is a similar situation. The gods can be real or fake, active or aloof, or whatever you see fit. In real life religion is tremendously varied. Most fantasy that I'm aware of have the gods as little more than background information, so I'd personally like to see one where they take a more active role.
  
  The only real point I question though is why are kingdoms so volatile? Are the people on this world prone to kingdom toppling riots? Are they xenophobic and prone to wiping each other out? This can all work, but I'd definitely find ways to work it into your story.