Joshua 17:13-18

13 When the Israelites became strong enough, they made the Canaanites do forced labor, since they didn't force all of them out.
14 Joseph's descendants asked Joshua, "Why did you give us only one region for an inheritance? We have a lot of people because the LORD has blessed us."
15 Joshua replied, "If there are so many of you, go into the forest! Clear ground for yourselves there in the land of the Perizzites and Rephaim if the mountains of Ephraim are too confining for you."
16 Joseph's descendants responded, "The mountains are not enough for us either. Besides, all the Canaanites living in the valley, in Beth Shean and its villages, and in the valley of Jezreel have chariots made of iron."
17 Then Joshua said to the descendants of Joseph, [the tribes of] Ephraim and Manasseh, "You are an important and very powerful people. One region is really not enough for you.
18 The mountain region will be yours as well. It is a forest, so you will have to clear it. All of it will be yours. But you must force out the Canaanites, even though they are strong and have chariots made of iron."