Joshua said to them, If you are a great people, go up to the forest, and cut down for yourself there in the land of the Perizzites and of the Rephaim; since the hill-country of Ephraim is too narrow for you.
The writer of the Book of Joshua noted carefully the failures of the tribes to drive the Canaanites out of their territories, as well as their successes in doing so (e.g., Caleb). The extent of their occupation of their land depended on the extent of their ability to annihilate the Canaanites by God’s power.