Around the Eldeen Reaches

The following information gives you an idea of what is around the Eldeen reaches:

The Eldeen Reaches

While the eastern edge of the Eldeen Reaches is fertile plains, much of the country
is covered in forest and has an ancient druidic tradition. Once part of Aundair, during the Last War the settlers in the Reaches were largely abandoned by the crown as it moved soldiers to the front. This in turn led to the rise of bandit lords in the eastern portion, which were put down by an army of druids and rangers from the deep forest. Angry at their abandonment, the people of the Reaches swore loyalty to the Great Druid Olian, an awakened oak who is said to be old beyond time itself.

The Eldeen Reaches have some of the most fertile farmland in all of Khorvaire, and
export vast amounts of food to the industrial machines of Breland and Karrnath; animal husbandry under the wing of the entrenched House Vadalis also has a large part in the activities of the nation. Though not exactly cosmopolitan, the people of the Reaches are more accepting of certain races than Khorvaire as a whole; these include
shifters (most of Khorvaire’s shifter population is found in the western part of the Eldeen Reaches) and orcs (the orcs of the Reaches have a druidic tradition older than human civilization on Khorvaire, and are thus respected in the area). House Vadalis has its primary holdings in the Reaches, and holds sway over several towns in the eastern portion.

The Demon Wastes

When the dragons and their couatl allies defeated the fiends at the end of the Age of Demons, binding their godlike leaders beneath the earth, many lesser fiends retreated to their nation’s capital in what is now called the Demon Wastes. The imprisoned fiends are openly worshipped here by the Carrion Tribes, which are composed of human barbarians and led by half-fiends and possessed warriors. The Lords of Dust is a powerful group of fiends who work to free their masters from their bindings beneath the earth.

The Shadow Marches

To most people, the Shadow Marches are seen as a land of savage humans and orcs in a fetid backwater. The area has a number of different clans and tribes and little real development; the only dragonmarked house with any presence here is the one that surfaced in the Shadow Marches, House Tharashk. They control the dragonshard trade
from the area and represent the only real centralized power in the area.

Droaam

Droaam is a monster kingdom. Split from Breland at the end of the Last War, Droaam was never very hospitable and became even less so with the coming of three powerful hags known as the Daughters of Sora Kell. Fighting free of Breland, Droaam is now known as a country ruled by hags, medusas, gnolls, lycanthropes, harpies, giants, ogres, and the like. These days the peace between Droaam and its neighbors is tenuous at best, and Droaam is mostly unwelcome to visitors.

Droaam is dotted with dungeons, crypts, necropolis', and ancient ruined cities. Many of these have routes into Khyber and are places for the Cult of the Dragon Below to use as base for worship.

Manifest Zones
In places, the boundaries between the planes are thin. Certain locations in Eberron have close affinities or connections to the other planes, allowing characteristics of those planes to spill over into the world. These areas are called manifest zones, since in these places the power of the planes is made manifest. Manifest zones appear everywhere in Eberron, and zones exist that link to all the planes except Dal Quor.
Manifest zones are, above all, unpredictable. That said, all manifest zones have two properties in common. First, a manifest zone is considered a part of both the Material Plane and the plane to which the zone is linked. An outsider is not considered extraplanar while in a manifest zone linked to its home plane, so it is impossible to use dismissal or holy word to banish an angel from the city of
Sharn, for example. Second, it is always easier to pass between the Material
Plane and the linked plane in a manifest zone. In most cases, magic is still required to move a creature from one plane to the other.

Three manifest zones in the Eldeen Reaches: Greenheart (linked to Lamannia), the Gloaming (linked to Mabar), and the Twilight Demesne (linked to Thelanis). Several known manifest zones linked to Kythri and Xoriat exist in the Shadow Marches.

Khyber
The west coast of Khorvaire saw the most intense conflicts with the daelkyr, and this region is riddled with passages to Khyber. Even though most of these were sealed away by the Gatekeeper druids and hidden from history and prying eyes, a few yet remain. In Droaam, the city of Cazhaak Draal sits atop a shaft leading to Khyber. During the ancient war, the daelkyr unleashed a horde of petrifying monsters against the goblins, and today a tribe of medusas dominates the region with the aid of domesticated gorgons, basilisks, and cockatrices. In the Demon Wastes, the Lair of the Keeper is said to contain thousands of souls trapped by the god of death and greed. Heroic songs tell of those heroes who have fought their way through the darkness to bargain for the souls of fallen friends.

Think of Khyber as something Akin to the Underdark in Fearun and your not far off the mark for its danger and wealth.