fence

How long will ye imagine mischief against a man? ye shall be slain all of you: as a bowing wall shall ye be, and as a tottering fence.

The country is encircled by a natural fence and is very difficult to attack and cannot be assailed by large forces, owing to the narrow passes, with theft overhanging precipices and deep ravines, and the rugged character of the mountainous regions which surround all the land.