Matthew Poole and continuators on Isaiah 42:11

11. Let the wilderness and the cities thereof lift up their voice, the villages that Kedar doth inhabit: let the inhabitants of the rock sing, let them shout from the top of the mountains .

Those parts of the World which are now like a Wilderness; not literally, for he speaks of their Cities in the next clause, but spiritually, desolate and forsaken of God, dry and destitute of the waters of Gods grace, and barren of all good fruits.

The Arabians: which were an Heathenish and Barbarous People, and well known to the Iews, and are synecdochically put for all Nations in the same circumstances.

Having mentioned Cities and Villages, he now adds those who dwell upon Rocks and Mountains, which are commonly more savage and ignorant than others, and therefore harder to be taught and reformed.