The Israelites did things that the LORD saw as evil, and the LORD handed them over to the Midianites for seven years.
References for Judges 6:1
The power of the Midianites prevailed over Israel, and because of the Midianites, the Israelites used crevices and caves in the mountains as hidden strongholds.
Whenever the Israelites planted seeds, the Midianites, Amalekites, and other easterners would invade.
They would set up camp against the Israelites and destroy the land's crops as far as Gaza, leaving nothing to keep Israel alive, not even sheep, oxen, or donkeys.
They would invade with their herds and tents, coming like a swarm of locusts, so that no one could count them or their camels. They came into the land to destroy it.
So Israel became very weak on account of Midian, and the Israelites cried out to the LORD.
This time when the Israelites cried out to the LORD because of Midian,
the LORD sent them a prophet, who said to them, "The LORD, Israel's God, proclaims: I myself brought you up from Egypt, and I led you out of the house of slavery.
I delivered you from the power of the Egyptians and from the power of all your oppressors. I drove them out before you and gave you their land.
I told you, ‘I am the LORD your God; you must not worship the gods of the Amorites, in whose land you are living.' But you have not obeyed me."