2 Because the power of Midian was so oppressive, the Israelites prepared shelters for themselves in mountain clefts, caves and strongholds.

Read Judges 6:2 Using Other Translations

And the hand of Midian prevailed against Israel: and because of the Midianites the children of Israel made them the dens which are in the mountains, and caves, and strong holds.
And the hand of Midian overpowered Israel, and because of Midian the people of Israel made for themselves the dens that are in the mountains and the caves and the strongholds.
The Midianites were so cruel that the Israelites made hiding places for themselves in the mountains, caves, and strongholds.