Judges 3:1, 2, 4

These are the nations that the L ord  left in the land to test those Israelites who had not experienced the wars of Canaan.  He did this to teach warfare to generations of Israelites who had no experience in battle.  These people were left to test the Israelites—to see whether they would obey the commands the L ord  had given to their ancestors through Moses. (Judges 3:1, 2, 4 NLT)