Dwarves

In the bygone era, Dwarves constructed an intricate network of tunnels connecting their sprawling underground cities throughout Arcanum, extending deep into the Underdark. Over time, this extensive network dwindled to only three colossal underground metropolises. The cataclysmic event unfolded when monstrous Deepspawns, demonic creatures unleashed by Dark Elves, overwhelmed the Dwarven realms.
Nowadays, these once-grand tunnels lay infested with monsters, prompting Dwarves to embark on perilous pilgrimages into the remnants of their old empire, now referred to as The Deep Roads. Remaining vigilant against the ongoing threat of Deepspawns, Dwarves seldom venture beyond their underground cities. The only exceptions occur when someone faces banishment or embarks on a holy mission. Even if successful, returning from such a mission is forbidden, deeming the individual tainted. Those who  remain on the surface are known as "the lost"
Despite these challenges, a faction of Dwarves opted for a different path, establishing mining settlements on the surface. Known today as Hill Dwarfs, these resilient individuals forged a new existence above ground.