In the 6th century BC the Edomites had made league with the Babylonians and then assisted them in the destruction of Jerusalem. Speaking of this very thing is Psalm 137:7, which exclaims:
“Remember, O LORD, the children of Edom in the day of Jerusalem; who said, Rase it, rase it, even to the foundation thereof.”
Likewise, from the Septuagint, from 1 Esdras 4:45 we read:
“Thou also hast vowed to build up the temple, which the Edomites burned when Judea was made desolate by the Chaldees.”
After the deportations of the last of Judah by the Babylonians, it is evident that those same Edomites moved into the land. A century or so later, Persian inscriptions place much of the province of Idumaea in the land of Israel. Ezekiel chapters 35 and 36 discuss the Edomite takeover of lands formerly belonging to Israel and Judah.