Umbra Hills

The  are a blasted wasteland at the base of the Cliffkeep Mountains, cursed forever by the demonic blood spilled in the final battle of the Scattered War.

Description
The hills no longer support animal life. The only plant that grows in the highlands is shadegrass, which boasts a unique and acrid flavor prized by spice traders across Exandria. So valued is shadegrass that spice-pickers often are accompanied by hired mercernary guards.

The hills are haunted, as the site of a deadly battle centuries before. When the moon is high, undead soldiers patrol the land, and shadow demons still walk the battlegrounds, still bound to the pact between Trist Drassig and Graz'zt, the Demon Prince of Indulgence.

The Tal'Dorei Council's influence rarely reaches Jorenn Village to the south, much less the unpopulated Umbra Hills themselves.

Battle of the Umbra Hills
As the Scattered War grew increasingly desperate for King Trist Drassig, Zan Tal'Dorei's rebel human forces and the allied Elves of Syngorn backed Drassig's army into a valley in the Emerald Highlands. Obsessed with the possibility of losing, Drassig pledged his service to Graz'zt, for whom the nearby Grey Valley had once been a bastion of influence, in exchange for a promise of victory. The bargain was accepted, and during the battle, a flood of fiends, including Graz'zt himself, poured into the battlefield in support of Drassig. All the continent's greatest mages fought in the battle, which soaked the hills in human blood and demonic ichor. Against all odds, Zan Tal'Dorei's forces prevailed, ended the Drassig bloodline, and banished Graz'zt back to his Abyssal prison.

However, the demonic blood that spilled that day permanently transformed the hills, once a flowering, sunny region known as the Emerald Highlands, into the cursed place it is today. Grass and flowers grow burnt and black, their sap tainted with the demon blood that permeated the earth. Because of this, the region was renamed the Umbra Hills.

Silver Rush
Around 742 PD, more than two centuries after the Battle of the Umbra Hills, rich silver deposits were discovered in nearby hills, drawing prospectors and common folk to Jorenn Village despite the nearness of the still-demon-haunted Umbra Hills. By 802 PD, a small group of mercenaries and vigilantes formed the Shadewatch to hunt the creeping dangers of the night.

Campaign 1: Vox Machina
The prison in which Vox Machina first found Percival de Rolo was where Jorenn Village imprisons their criminals, and was located in the Umbra Hills far north of Westruun. The adventurers had traveled to the area to slay a nightmare that had been spotted in the area; Eskil Ryndarien needed the skull of a nightmare to safely extract a phylactery from Grog Strongjaw's chest. It turned out the nightmare was being summoned by cultists in the local mining guild.

By 812 PD, Shademaster Arhanna Lewyn was sending a trio of Shadewatch agents into the Umbra Hills or to Gatshadow Mountain weekly.

The adventure hook Shadows of the Past in the original Tal'Dorei Campaign Setting sourcebook, set in 812 PD, involves the discovery of a magic longsword inscribed with the words "Trist Drassig" in the Umbra Hills, but those who claim the blade are, starting one week later, attacked by shadows nightly.

Trivia
The umbra is the darkest part of a shadow, where the light source is fully blocked.