21:1 desert of the sea. The context indicates that this desert was the wilderness of Babylonia bordering the Persian Gulf.

21:2 Elam: besiege, O Media. The Medo-Persian empire would eventually defeat the great Babylonian empire (note Isaiah 21:9). This prophecy was fulfilled almost two centuries after Isaiah’s time. Yet Isaiah prophesied of it.

21:9 Babylon is fallen. See above note on Isaiah 21:2.

21:11 Dumah. Dumah was a son of Ishmael (Genesis 25:14) and Seir was a Horite (Genesis 36:20), but both lands became possessions of the Edomites, descendants of Esau, and longtime enemies of Israel. The picture is of Edom calling to the prophet and asking the time of night. As a faithful watchman, Isaiah warns that even though daylight is near, night will come again; the people of Edom urgently need to “return” (Isaiah 21:12) to the God of their father, Isaac.

21:13 Arabia. The Arabs, including “the children of Kedar” (Isaiah 21:17), were descendants of Ishmael, and these also would fall to the Assyrians. The Dedanim were Hamites, descendants of Cush, who once also had inhabited southern Arabia.

21:14 prevented. That is, in terms of old English usage, “preceded” or “anticipated.”