I do not particapate (yet) in the Kingdom's Map but maybe I have some suggestions.
-I would not use the word 'planet', in medieval times they hardly knew what a planet was. The ancient Greek did (help me, my Greek friends, planetar means something like 'to roam' as the planets had no fixed places in the firmament like stars) but did not see them as something people could live
-Keep it as general as possible ( for instance, Middle- Earth as used in Lord of the Rings was brilliant), with no references to nowadays history
-Indeed nothing like "Empire" or "Kingdom" because this world is bigger than that.
-I like something with the word "Terra", for instance "Terra Nova", Playmoterra, Terra Plastica or maybe "Terrabeck"
I would love to participate and I'm sure my armies would easily crush all your armies, even when they join forces... (

) but I have really lack of time and I want to finish my chess sets and the Randolph story first..