Fairbairn on the Blending of the Edomite and Jewish Nations
Free Church of Scotland minister Patrick Fairbairn (1805-1874), in his Imperial Bible Dictionary, comments on the migration of the Edomites into Judea, even within twenty miles of Jerusalem, and the consequent melding of the Edomite and Judahite people:
“We see therefore that the Edomites of Selah or Petra are also called Nabateans; and in yet later times we shall find the names of Arabia Nabatea and Arabia Petra both given to the desert country of Edom. At the same time we find an alteration in the limits of Edom, which were now removed as far as the hill country of Judea. Historians rarely speak of any but the governing class in a nation; so much so, that if from any cause these are removed and a lower class rises into notice, the country seems peopled by a new race of men; thus it was in this southern portion of Judea. When the priests and nobles [of Judah] were carried into captivity by the Babylonians, the peasants left behind readily formed one nation with the Edomites, with whom they were more closely allied in blood and feeling than with their Jewish masters, and henceforth we shall find two meanings belonging to the word Edomite or Idumean; sometimes the name will belong to the Arabs of the desert about Petra, but the Greek name of Idumean more usually belongs to the less wandering race of southern Judea, within twenty miles of Jerusalem; the wilder Edomites or Nabateans being driven back to the south of the Dead Sea.”
— Patrick Fairbairn, The Imperial Bible Dictionary, Volume I, Idumea, pages 777-778
For a longer treatment of this subject, please read the article Who Were the People Calling for the Crucifixion of Christ?