Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
The following commentary covers Chapters 15, 16, 17, and 18.
In chapters 15 and 16 Moab is judged. They are warned that the throne of David shall be established, and the oppressor consumed out of the land. In chapter 17 we have the invasion of armies from the north, the assembled nations. Damascus is overthrown. Israel shall be but as a few berries on the outmost branches. Nevertheless they shall look to their Maker, and the gathered nations shall perish before the manifested power of God. The outline of this last invasion of Israel gives rise to a brief but very clear prophecy of their condition in the last days, and which is contained in chapter 18. They shall be restored by means of some powerful nation, outside the limits [See Note #1] of their then national relationships; but Jehovah stands apart from His own relationship with them, though ordering all things. Then, when Israel shall begin to bud as a vine in the land, they shall be given up as a prey to the nations. Nevertheless in that time they shall be brought as an offering to Jehovah, and shall themselves bring an offering too.
Note #1
The rivers of Cush, Nile and Euphrates.