|Region||Drarthiel, Imgangreth, Onvorn, Phangul|
Beneath the southern regions of Brucrumus is a vast expanse of subterranean passages. The largest of these passages is the Great Tradeway. It forms an "X" like shape spanning the Underdark regions under the Northern Hordelands, Lands of Purity, Grashakh, and Hells Womb.
The southeast to northwest axis begins southeast at the base of the Pyramid of Merioss in the Drarthiel region. From there it passes above the Green Nebulous, then along a great passage for thousands of miles away to the gates of Dienkigec. Both of these spectacular places, one an old Lith-Crillion R&D center patrolled by Pyrmidian Ghouls, and the other built in the hardened husk of one of Krephus's offspring, led to theories on who built the Great Tradeway. Some say it was the Lith-Crillion, others just a great worm aimlessly boring away.
The opposite axis of the Great Tradeway starts at Amurlax, a subterranean fortress beneath the surface city Vraga Moltus. From there it ends at the southwest side of the Ebonmurk, then picks up again on the opposite side. It continues for another thousand miles, ending near the Sphere Fungal.
Countless side passages, leading to subterranean empires and other wonders, merge with the Great Tradeway. It has been expanded in many areas, with the most notable being Sidari-Nyx. This extension was done to open trade routes to unlinked tunnel systems.
The Great Tradeway has seen numerous wars and battles fought along its very wide passages. These are usually the result of someone exerting excessive control of an area of the passage or excessive tolling and taxing of goods. There are a lot of towns, cities, and empires that depend on the free movement of goods along the Great Tradeway. Most are signatories to treaties keeping it open for fair trade and largely de-militarized.