C. F. Keil and Franz Delitzsch on Joshua 23:4

Jos 23:4

He (Joshua) had now divided by lot among the tribes of Israel as their inheritance these still remaining (Canaanitish) nations, as the Lord had commanded (Jos 13:6-7), “from Jordan and further all the nations, which I have exterminated (i.e., which Joshua had destroyed when Canaan was taken), and the great sea (for 'to the great sea') in the west.” The breadth of the land of Canaan is here given in a peculiar manner, the terminus a quo being mentioned in the first clause, and the terminus ad quem (though without the preposition עד) in the second; and through the parallelism which exists between the clauses, each clause is left to be completed from the other. So that the whole sentence would read thus: “All these nations which remain ... from Jordan to the great sea, also all the nations which I have cut off from Jordan, and to the great sea westward.”