Charles Ellicott Commentary Isaiah 21:1

"The burden of the wilderness of the sea. As whirlwinds in the South sweep through, it cometh from the wilderness, from a terrible land." — Isaiah 21:1 (ASV)

The burden of the desert of the sea ... — The title of the prophecy is obviously taken from the catch-word “the desert” that follows.

The “sea” has been explained as follows:

1. as the Euphrates, just as in Isaiah 18:2; Isaiah 19:5, it appears to be used for the Nile (Cheyne).
2. As pointing to the surging flood of the mingled myriads of its population.
3. Xenophon’s description of the whole plain of the Euphrates, intersected by marshes and lakes, as looking like a sea, perhaps affords a better explanation.

As whirlwinds in the south ... — The “South” (or Negeb) is here, as elsewhere, the special name of the country lying south of Judah. The tempests of the region seem to have been proverbial (Zechariah 9:14; Jeremiah 4:11; Jeremiah 13:24; Hosea 13:15).

So it cometh. — The absence of a subject to the verb gives the opening words a terrible vagueness. Something is coming from the wilderness, a terrible land, beyond it. The “wilderness” in this case is clearly the Arabian desert, through part of which the Euphrates flows. The context determines the “terrible land” as that of Elam and Media.