The mountains; understand by a metonymy the woods or forests upon the mountains, which in those hot countries, when they had once taken fire, either by lightning, or by the design of men, or by any accident, did burn with great speed and irresistible violence.
Related Commentaries of Psalms 83:14
Psalms 83:14
14 As the fire burneth a wood, and as the flame setteth the mountains on fire;