The world of Prester is divided up into two lands—Anatoray and Disith—and the only way of reaching one from the other is to cross the Grand Stream. Disith is all but completely undescribed within the series—all that is truly known of it is that due to a rapidly falling temperature akin to an ice age, its people are attempting to evacuate to Anatoray. It is Anatoray that serves as the primary setting of Last Exile. It is a monarchy, and its citizens have few complaints of its leadership. It is an arid, mountainous land well into its Industrial Revolution—steel and steam engines are common. Though it is plagued by drought, it is thus able to survive due to relatively well-developed water purification technology—though most settle for potable but obviously dirty groundwater. However, First Water (the purest available in Anatoray, what modern society would call common filtered drinking water) is still not beyond the means of most - they simply treat it as an extravagant commodity. Also, due to the presence of an ore known as Claudia, it is currently experiencing a Golden Age of Aviation in the form of lighter-than-air craft known as Vanships. As Anatoray's mountainous terrain is too dynamic for rail transport, these have become quite prevalent. Gas-lit beacons dot the landscape, and aerial refueling stations extend the range of Vanships across the land.
As the series starts, it is difficult to understand how the two lands of Anatoray and Disith can only be traveled between by flying high into the sky, entering the Grand Stream, and flying through a bottle-like hurricane out to the other side. In the last episode, when the great vessel Exile is finally found and used to dissipate the Grand Stream, we see that the planet itself is actually two smaller planets joined together into an hourglass shape, with each world facing the other. Once the skies are clear, anyone standing on the surface of either land can look up and faintly see the landscape of the other.
- It's worth mentioning that the technology developed for Prester provides an understanding of Prester's geography. Air ships, not sea going vessels are seen. This leads us to believe that Prester must not have vast oceans, like Earth (which is 70% water). Instead technology was developed to command the skies, especially in light of the fact of Prester's unusal shape, the Grand Stream & The Guild. Another reason for Prester's technology shift can be seen with how scarse water is for the people of Prester. Even though The Guild seems to have a monopoly on First Water, water doesn't seem to be everywhere. If Prester had vast oceans, it wouldn't be farfetched to assume desalination processes would be used to reclaim pure water. Desalination is not difficult, and was used early on on Earth, 49 BC maybe even earlier.
- This is what the phrase written on the book at the beginning of every episode means:
λαστ εξιλε ιν τηε βοττλε "last exile in the bottle"
The phrase is written in Greek letters, like all other text in the series, and refers to the fact that Prester is a world shaped like a bottle, or an hourglass. It has a narrow portion in the very middle, which is filled with the Grand Stream until the last episode, and it widens out at either end, and these ends contain the miniature binary planets that come to be called Anatoray and Disith.
The only time Prester is truly shown in this form is on the last episode when the cast looks out from the deck of Exile and sees Prester from outer space. Up until that point, the writers and art directors of the series had been playfully toying with revealing that fact by spreading the hourglass shape all over the series on various maps, icons, artwork, and royal emblems.
In the series, during the 11th episode, the character Alister uses a sextant to plot her position according to the stars. This is when she utters the phrase, "The stars have become unreliable." She is referring to the slow, spinning motion that the enormous hourglass-shaped world of Prester is making in the heavens, giving the stars an erratic pattern across the sky when viewed from Anatoray.