What does Isaiah 18:1 mean?

The seven verses in this short chapter seem not to contain an oracle "against" another nation, as do others. This may simply be setting up the following chapter which contains a specific prediction against Egypt (Isaiah 19:1).

Commentators are not resolved on the meaning of "whirring wings" in this verse. Isaiah says "ah"—perhaps meaning something like "woe"—to the "land of whirring wings." Those wings might refer to the many insects in that region or it may be speaking of the sails of the swift-moving boats that travel the rivers there.

Scholars suggest that the area Isaiah describes as being "beyond the rivers of Cush" might have been located along the Nile River south of Egypt. This would have been in a region sometimes called Ethiopia, which is different from the modern nation of Ethiopia. During this time, Ethiopian kings were in the process of trying to unite all of Egypt under their rule.