The Chronicles of Erdon
Artifices of Protection
These two mysterious magical contraptions afforded Archlond imperviousness to the twin threats of Chaos and Evil; effectively rendering the continent undetectable to creatures of these alignments, even blocking most divinations, and barricaded from any beings that managed to discern the continent. When the southern artifice was destroyed it opened the continent to Chaos, and the highest mountain collapsed and spilled out into the sea, leaving a great chasm between formerly adjoined mountains. This ravine was called the Gap. The fan-like wash also provided a stable beachhead whereupon the barbarian ships landed. When the barbarian hordes eventually pressed their way through the Gap and overran the inner cities, they discovered that there was another artifice in the northern mountain range; it failed in similar manner, and the Gaps were renamed the Northern and Southern, respectively.