שופטים, פרק ו׳, פסוק ב׳

Relentless pressure from nomadic invaders forced the Israelites to completely alter their way of life. Although Midian was a small desert nation, they acted with unusual boldness and extreme cruelty, driven by a desire to destroy and steal the crops of the land [ביאור שטיינזלץ, חומת אנך]. The threat from these invaders grew gradually and continuously until the Israelites were forced into desperate action just to survive [מצודת ציון, מלבי״ם].

Driven by an existential need to protect themselves and hide their harvest from the raiders, the Israelites fled to the mountains and prepared three different types of shelters and defenses [מצודת דוד, ביאור שטיינזלץ]. They sought refuge in ordinary, natural caves [רש״י]. For greater security, they also constructed strong, protected fortresses [רד״ק, מצודת ציון]. These strongholds were built deep within the forests, where the people would cut down trees and arrange them into thick protective walls around their living areas [רש״י].

The third type of preparation involved specialized mountain structures. The primary approach among commentators is that these were hidden underground spaces built with a tiny, unnoticeable opening or top window just large enough to let in a ray of daylight [רש״י, רד״ק, מצודת ציון, מלבי״ם]. However, a different perspective suggests these were not hiding spots at all, but rather fire beacons and torches positioned high on the peaks. Whenever the enemy approached, these beacons would be lit immediately, serving as an early warning system so the residents could rescue their property before the raiders arrived [מלבי״ם].