Judges 3:2-4

2only in order that the generations of the sons of Israel might be taught war, at least those who had not experienced it previously).

3The remaining nations are: the five lords (governors) of the Philistines, all the Canaanites, the Sidonians, and the Hivites who lived on Mount Lebanon from Mount Baal-hermon to the entrance of Hamath.

4They were [allowed to remain] for the testing of Israel, to determine whether Israel would listen to and obey the commandments of the Lord, which He had commanded their fathers (ancestors) through Moses.