Judges 6:4

‘ And they encamped against them, and destroyed the increase of the earth as far as Gaza, and left no sustenance in Israel, neither sheep, nor ox, nor ass.'

They took up temporary residence over a wide area ‘as far as Gaza', where they came to a stop because they came up against the Philistines. And they did it for the purpose of burning the crops, vines and olives and stealing the livestock. Thus a large part of central Israel was affected, and probably some Philistine territory. But the main sufferers were Israel. They were left to starve. The only way they survived was by what they produced, or hid away, in their hiding places in the mountains.