Jeremiah 49:39 - Matthew Poole's English Annotations on the Holy Bible

We had the like promise as to Moab, Jeremiah 48:47, and as to Ammon, Jeremiah 49:6; the same latter days either signify after many days, or in the time of the Messias. In the former sense it may refer to Cyrus, who conquered Persia. In the latter sense it is referred to the spiritual liberty which some of these poor heathens were brought into by the gospel. We read, Acts 2:9, that some of these Elamites were at Jerusalem at Pentecost, and were some of those converted to Christ.