It means something that makes travel difficult. Like mountains or a fast river. Or you have no legs, or you are four years old, or you have four small children. Or no money.
They are a barrier to travel and settle ment because of the snow and there peaks
Money, visa
If you want too...
Yes: humpback whales travel through the Great Barrier Reef on their annual migration.
Barrier
Exceeding the sound barrier refers to speed of travel, not loudness of sound. A speaker cannot "exceed the sound barrier".
Fear of the unknown.
Drought
The sound barrier
Drought
jackass
A Barrier