Adam Clarke on Joshua 23:4

I have divided - these nations that remain - The whole of the promised land had been portioned out, as well those parts which had not yet been conquered, as those from which the ancient inhabitants had been expelled. The Canaanitish armies had long ago been broken in pieces, so that they could make no head against the Israelites, but in many districts the old inhabitants remained, more through the supineness of the Israelites, than through their own bravery.

From Jordan - unto the great sea - All the land that lay between the river Jordan, from Phiala, where it rose, to the southern extremity of the Dead Sea, and to the Mediterranean Sea, through the whole extent of its coast, opposite to Jordan.