The War of Horrors
The Shadow Marches are a swampy, remote region of Khorvaire filled with fetid bogs, ramshackle villages and rich deposits of Eberron dragonshards. House Tharashk is the only major economic power in the area, as it controls the harvest and export of the region’s dragonshards. Despite the Marches’ mineral wealth, it remains a dark, decrepit and impoverished country.
Thousands of years ago, the Shadow Marches were the epicenter of the Daelkyr War, an invasion from Xoriat, the Realm of Madness. The inhabitants of Xoriat were known as the daelkyr, and they possessed a horrific power to reshape living flesh. During the incursion, the daelkyr flesh-sculpted living beings to create both weapons and troops for their campaign.
Only the intervention of the Gatekeepers — a druidic sect trained specifically to repel the extra-planar invasion — brought a conclusion to the conflict. Despite their assistance, the Shadow Marches never fully recovered. To this day, daelkyr abominations, artifacts and half-bloods still reside in hidden enclaves throughout the swamps.