Somnum was the name of a western portion of a landmass that dominated the known world. As the seas surrounding the landmass were extremely deadly to traverse, the continent of Somnum represented the majority of what Mortalkind had been able to explore. Some smallfolk cartographers believed that the west resembled the shape of a Dragon's skull, and called it the "Head of the Greatwyrm."
During the Age of Giants, the smallfolk settled west of the Neck of the Greatwyrm, and eventually drove out the great predators of the continent such as dragons and Giants. Sending them into the east past these mountains, the "Body of the Greatwyrm" became known as the Giantlands, a fraught territory largely unexplored by mortals. The dangers of these lands generally kept smallfolk away, as did the Sea of Clouds, the Sea of Trees, and the Wightmist Archipelago.
Over time, the finding of Epochal Artifacts decided the politics of Somnum, as their might directly lead into how territories were formed. The Human-majority nations of the Common League, the Elthysi Sovereign, and the Scycaen Imperium dominated most of the continent.
Other nations had to develop unassailable borders to remain sovereign: the Elven citadels of Ardhon Miniel and Xilvalur were protected by magic woodlands and arcane wards; the Dwarven kingdoms of Brazenthrone and Skypeak were tucked in impenetrable mountain homes; and the mysterious floating mountains of Ty-Pharess were unapproachable by sea.