Rashi: Before those who come upon them from the north, the cities of Eretz Yisrael were closed, from fear of Nebuchadnetzar.

Radak citing Targum Yonasan: These are the cities of the south, i.e. of Yehudah. They are called 'of the south' due to the next verse, which discusses the destroyers and captors coming from the north. The cities are desolate; no one leaves or enters. No one closes or opens. It says also in Yeshayah (24:10) "Kol Bayis mi'Bo."

Malbim: Yerushalayim is in the north of Yehudah. Nebuchadnetzar came from the north. In the middle of the siege, Pharaoh's army came to help Yehudah, and the Bavliyim went away from Yerushalayim (Perek 37) to face Pharaoh's army, which came from the south. Then, Bavel's army was in the south. The cities were closed via the enemy, who captured them.

Radak: Since the king (Yehoyachin) was exiled, it is as if all were exiled, for they are destined to be exiled soon. The great ones among them were exiled with Yehoyachin.

Malbim: All the fortified cities were captured.

Rashi #1: Yehoyachin will not fight; he will leave and be exiled b'Shalom.

Rashi #2, Targum Yonasan: [Exile] is Tashlum (payment) for their sins. Radak - Yonasan expounds the plural Shelomim to teach also that they were totally exiled.

Radak: The matter (Haglas Yehudah Kulah) is repeated in different words. Shelomim is like Kulam, i.e. Shelemim. Also "Musar Shelomenu Alav" (Yeshayah 53:5) is like Musar Kulanu ¹ .

Malbim: The Bris of Shalom that you had with Pharaoh was exiled from you.