Today we continue reading a collection of oracles against the nations that began in chapter 13. I suspect this collection is arranged thematically rather than chronologically. That is, though they are all attributed to First Isaiah, my guess is he spoke them at different times and only later did some redactor group them together.
Isaiah 18:1-7 is an oracle against the nation that was known in Hebrew as Cush but which we are more likely to call Ethiopia. The oracle is bracketed by a pair of verses describing the Cushites in the same words:
a people tall and smooth-skinned,
...a people feared far and wide,
an aggressive nation of strange speech,
whose land is divided by rivers.
(Isaiah 18:2 and 7)
The smoothness of their skin may suggest that the Ethiopians, unlike the Judahites and most of their neighbors, were clean-shaven. During Isaiah's time there were Ethiopian pharaohs who ruled over Egypt. The point of this oracle is that the fearsome Cushites will one day submit to YHWH and bring tribute to Jerusalem.
Isaiah 19:1-15 is a poem describing disasters, and the resulting civil unrest, that YHWH will bring upon Egypt. If Judah is turning to Egypt for aid against the Assyrians, Isaiah says, it won't work out well.
Next comes a prose section (Isaiah 19:16-25) in which the prophet declares that Egypt will submit to Judah and that, one day, Assyria, Egypt, and Judah will live in peace under YHWH. Isaiah is universalisitic like that.
Chapter 20 tells how Isaiah spent three years walking naked and barefoot as a prophetic act-sermon to illustrate that Egypt and Cush ("those in whom we hoped" v. 6) would be taken captive and led away--naked and barefoot--by the Assyrians. Public nudity was considered shameful in ancient Israelite culture.
Isaiah turns his attention toward Babylon in 21:1-10. The watchman's refrain "Babylon has fallen, has fallen!" will be echoed in the book of Revelation (14:8, 18:2) where John the Seer equates Rome with Babylon. The actual Babylon fell to Persia in 538 BCE.
Isaiah 21:11-12 is a short, curious oracle against Dumah (verse 11), a town in northern Arabia. A footnote in the New International Version suggests that Dumah, which means "silence," is intended as a wordplay on "Edom." Maybe. The town of Dumah appears to be a long way off from Edom on the maps I've consulted. The Septuagint does insert "Edom" where the Masoretic text says "Dumah" and "Seir" (later in verse 11) is unquestionably Edom. I'm not sure what to make of this short passage. A note in the CEB Study Bible says
[T]he oracle headings in Isaiah 21:1,13; and 22:1 refer to indefinite locations, leaving the referent of this one in doubt. What sounds like a chance exchange between a a sentinel and an inquirer minimizes the impact of the momentous news of Babylon's defeat, perhaps as if to say, "Empires come and go."
Isaiah 21:13-16 is an oracle about "the desert." It encourages the people of Dedan and Tema towns, like Dumah, in northern Arabia to welcome Judahite refugees. The Kedarites who, according to Genesis 25:13, were offspring of Ishmael, are in for judgment.
Isaiah's oracle in 22:1-14 comes close to home. The people of Jerusalem are partying on the rooftops, celebrating a victory--or at least a non-defeat--and putting their trust in human abilities, weapons, preparations, and resources. They should have been repenting, not partying. Isaiah says YHWH is still mad.
The LORD Almighty has revealed this in my hearing: “Till your dying day this sin will not be atoned for,” says the Lord, the LORD Almighty.
In 21:15-19 the prophet gets personal. It seems a self-aggrandizing government official named Shebna has been building a monumental tomb for himself. (Archeologists have uncovered such a tomb though the name is partially missing). Isaiah says that he will be replaced by someone named Eliakim. The end of the chapter gets a little confused but it may be that Eliakim engages in nepotism and proves no better than his predecessor.
The picture of the inscription from what may be Shebna's tomb came from wiki. Scripture quotes are from the New International Version.
Next: Isaiah 23-27