‘ And the hand of Midian prevailed against Israel, and because of Midian the children of Israel made themselves storage holes which are in the mountains, and caves and defence points.'
The Midianites and their allies would time and again suddenly, silently and swiftly descend on Israel, robbing, raping and looting, and the Israelites thus prepared themselves places in the mountains where they could hide provisions and when necessary find refuge and defend themselves, away from the marauding camels. Compare Isaiah 2:18-20. The mountainous areas of Israel abound with such natural caves and dens which could be turned to this kind of use.