Isaiah 21:2

A grievous(lit. "hard") vision is declared unto me by the "watchman," Isaiah 21:6. "Hard" may mean either "calamitous" (1 Kings 14:6) or "difficult," "hard of interpretation" (John 6:60).

the treacherous dealer … spoileth Cf. ch. Isaiah 24:16. It is difficult to decide whether this is a description of the besieging foe or of the conduct of the Babylonians towards their captives. The former view might be defended by Isaiah 33:1 (assuming that the Assyrians are there alluded to) but it requires us to substitute for "treacherous dealer," "robber," which is not the exact sense of the word. The other alternative is supported by the last clause of this verse (see below).

Elam … Media The dominions of Cyrus. The former lay east of the Tigris and north of the Persian Gulf; Media was the mountainous district adjoining it on the north. Cyrus, according to the Babylonian records, was originally king of Anzan, in the north of Elam; in 549 he conquered Media, uniting the two in one kingdom. The name "Persia" never occurs in pre-exilic books.

all the sighing thereof The misery produced by her (Babylon's) ruthless oppressions. The verb shews that Jehovah is the speaker.