Malmus is an ancient empire founded early in the Horgon Era. The roots of this empire come from a band of fomorian refugees that managed to escape their ancestral lands in Kriav's Underdark. After eluding illithid pursuers and attendant mind slaves, the fomorians used a null mine to collapse the feydark fissure behind them. The fomorians now found themselves in the deeps of another world entirely. In Brucrumus's Tier 2 Underdark they founded the village Telostyxe. Over the centuries that followed they added those around them to their holdings, first by enslaving them, and then with large adversaries by military dominance. By the middle of the Horgon Era, Malmus became a respectable force in the Underdark region Melgrinn with several city-states serving as vassal states.
Late in the Horgon Era, troglodyte explorers discovered the Lirhazi Cavity. After a climb of more than two miles up, they found themselves in a large cavern of the Onvorn region. A couple years later, other Malmus explorers found passages leading to the surface. They began raiding the outlying settlements and mining camps of Guthnimor and then those of Hanthaerion in the First Epoch. Today, these two surface nations have to post strong patrols and garrisons on their borders with the Ikhen swamp.