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.
"They left no sustenance in Israel"  (Judges 6:4).  The ruthless invaders with their myriads of armed men with their flocks, herds and camels were literally taking over the central region of Palestine, and the Israelites were sorely pressed even to make a living.