Since you are putting some thought into the defense of your border i figure i shall supply you with some additional information.
The western mountain range hosts the highest reaching mountains in all of Faraway. Their lofty reaches are a cold and hostile place home only to roving bands of goblins and beastmen, the occasional giant and the hardened mountain men of the Iron region.
Crossing from the West to the east via the mountain range is a suicidal task at anytime but the very height of summer. During this time the mountain men can lead those willing through a series of narrow and dangerous tracks that crest the lower central section of the range to the south of Blackwell castle.
The main flow of traffic through the mountains is in the hilly lands at the northern most tip of the realm. This area sees a steady stream of merchant caravans passing along the traders roads, crossing from the western to eastern side of Faraway. This area has often been rife with bandits and beast-men picking on the less defended traveler as they make there way through the region.
As for traveling under the mountain there are no known passageways in the cave systems that connect from one side to the other. If there are any linking passages they would only be known to the roving goblin tribes.
If you have any further questions let me know.
A hundred years from now, D&D 99.5E will have pared the game down to four skills - Hurting, Breaking, Living, and Talking. Talking will be a dump stat for most classes.