In a range of hills, or especially of mountains, a pass (also gap, notch, col, sadle, bwlch, brennig or bealach) is a lower point that allows easier access through a range. On the route through the range, it is locally the highest point on the route. Since many of the world's mountain ranges have always presented formidable barriers to travel, passes have been important since before recorded history, and have played a key role in trade, war and migration.