The Hollow is a vast hollow sector under the ground, beneath the Grottos. It is one impossibly vast cavern pocked by huge columns of stone holding the world up. There are regions of it that are miraculously verdant.

Countries:

1. Alkor Stair is a dwarven-built stone stairwell that runs from the Grottos above to the Hypogaeum below. It is built next to a column, for they realized that they could not carve into the column without risking the entire realm.
2. City Under the Stair: the people of the City Under the Stair have no access to Alkor Stair, and thus, they find it an object of fascination. This massive, nation-sized city is of mixed underground beings, and their lives are dominated by the Stair. It is next to a column.
3. The Crag Kingdom is a nation of living stones of all sorts. It is a vast nation beneath Dabusen that contains a few dozen different races, all serving a great living stone tribe. It has one column.
4. Grand Expanse: The Grand Expanse is one of the largest nations in the world, a huge region (holding five columns) where the chthonians dwell. Olitiau are also found here. Parts of it are under Starfall, Palhur, Taggarus, Mati, and Ansulym.
5. Meduin is an city built among waterfalls of the Hollow, where the Tunbarian chtonians dwell under the Wyren Ocean. There are no columns here.
6. Orday is a chthonian nation under Ranu that is where the Ordish chthonians dwell around a single column in a fortress city.
7. Pangroth is the second largest underground nation, beneath Taggarus and Mati. It has two columns. It is where the borers live amidst vast underground jungles and warrens.
8. Roots of the World reach through here as well. They serve as a column.
9. Thaurgkall is a tyrannical feudal state under Jesenya with no column. The Thaurgkallian chthonians rule here.
10. Umphand is under the Great Southern Ocean, and it is a powerful nation of outcasts from the Crag Kingdom. It has no columns.
11. Zul'Kranak is under Jesenya, Mati, and Lyrilla, and it is where troglodytes dwell. It is holds one column.

Purple are the columns.