A civilization exists for several hundred years, developing its own language. such a civilization probably has been?

A civilization exists in a mountain valley for several hundred years developing its own language in isolation from nearby civilizations such a civilization probably has been

- Protected from invasions by the mountains around it.

- Isolated by mountains or some other physical barriers.

- Offered a bigger supply of national resources, like the Aztecs.
Isolated by mountains or some other physical barriers.