Isaiah 21:16-17. “For thus hath the Lord said unto me, Within a year, according to the years of an hireling, and all the glory of Kedar shall fail. And the residue of the number of archers, the mighty men of the children of Kedar, shall be diminished: for the Lord God of Israel hath spoken it.”
This prophecy has been given a specific time element: Within one year it would be proven as true or false. History tells us that it was indeed true.
Kedar is another descendant of Abraham through Hagar and Ishmael (Gen. 25:13). It is just north of Tema and Dedan.
All the mighty archers would be so diminished in number that they would be helpless against the Assyrian armies as they rolled through the land. The devastation would be complete.