cities - in a region not wholly waste, but mainly so, with an oasis here and there.
Kedar - in Arabia-Deserta (Isa 21:16; Gen 25:13). The Kedarenians led a nomadic, wandering life. So Kedar is here put in general for that class of men.
rock - Sela, that is, Petra, the metropolis of Idumea and the Nabathoean Ishmaelites. Or it may refer in general to those in Arabia-Petraea, who had their dwellings cut out of the rock.
the mountains - namely, of Paran, south of Sinai, in Arabia-Petraea [Vitringa].