The equator of this world is around 8000 miles (about 1/3 that of earth, so it's a smallish world). The great desert there, which more or less defines Tarth/Parthann's collective borders, is about 1/3 of that. So figure 2300 miles from one end of the desert to the other. Tarth's western border is hardly set, and they have disputes with the Free Cities over exactly where the lines are.
The distance from the ocean to the south edge of the map, I believe we decided, is about 800 miles, with next to nothing explored south of that (although Sprig and I had an idea for what to put down there in a future "expansion"). We don't, on the other hand, have a really solid reason for WHY the world isn't explored south of that, though Kije put a mountain range at the south edge of Bregoran. The river would probably have cataracts, that make it unnavigable, and therefore undesirable to explore. But the desert, well, maybe there just aren't any known oasis locations south of that. Maybe superstition. Maybe Darklings stop them. *shrug* work with me on the reasons there.
In terms of square miles, the desert as a whole is around 1.84 MILLION square miles.
Roughly speaking, Parthann's territory is about 368,000 square miles, (800 miles from the ocean southward, around 460 miles east-west on the average.) while Tarth makes up the rest of that, 1900 miles east to west and covering nearly 1.5 million square miles.
All of that sounds impossibly big until you realize that the US has a square milage of like 3.62 million. Russia is almost 7 million. California is 156000. So we're still talking about very big nations for the ancients, but Egypt was almost exactly the same size as I just described for Parthann, so it's not unreasable.
