dealeth treacherously - referring to the military stratagem employed by Cyrus in taking Babylon. It may be translated, “is repaid with treachery”; then the subject of the verb is Babylon. She is repaid in her own coin; Isa 33:1; Hab 2:8, favor this.
Go up - Isaiah abruptly recites the order which he hears God giving to the Persians, the instruments of His vengeance (Isa 13:3, Isa 13:17).
Elam - a province of Persia, the original place of their settlement (Gen 10:22), east of the Euphrates. The name “Persia” was not in use until the captivity; it means a “horseman”; Cyrus first trained the Persians in horsemanship. It is a mark of authenticity that the name is not found before Daniel and Ezekiel [Bochart].
thereof - the “sighing” caused by Babylon (Isa 14:7, Isa 14:8).