JDG 3:1

1 At that time there were still many people-groups in Canaan. Yahweh left them there to test the Israeli people. But many of the Israelis in Canaan were ones who had not fought in any of the wars in Canaan. So Yahweh also left those people-groups in Canaan so that the descendants of those who had not fought in any of the wars might learn how to fight.