The year of deliverance to Israel was come, and therefore the Lord inclined the hearts of their enemies to gather together. See Judges 4:6-7; Micah 4:12-13.
Related Commentaries of Judges 6:33
Judges 6:33
33 Then all the Midianites and the Amalekites and the children of the east were gathered together, and went over, and pitched in the valley of Jezreel.