The children of Israel did that which was evil in the sight of Yahweh: and Yahweh delivered them into the hand of Midian seven years.
"Israel made them dens ... and caves ..."  (Judges 6:2).  The severity of Israel's oppression under Midian is indicated by the fact that many Israelites resorted to hiding in dens and caves, a phenomenon of the limestone ridges in Palestine, but the text indicates that Israel prepared large numbers of these dwellings as hiding places from their enemies, and also, as being more easily defended against attack.