Sela or Selah
(the rock), (2 Kings 14:7; Isaiah 16:1) so rendered in the Authorized Version in Judges (see later 2 Chronicles 25:12), probably known as Petra, the ruins of which are found about two days journey north of the top of the Gulf of Akabah and three or four south from Jericho and about halfway between the southern end of the Dead Sea and the northern end of the Gulf of Akabah. It was in the midst of Mount Seir, in the neighborhood of Mount Hor, and therefore Edomite territory, taken by Amaziah and called Joktheel. In the end of the fourth century B.C. it appears as the headquarters of the Nabatheans, who successfully resisted the attacks of Antigonus. About 70 B.C. Petra appears as the residence of the Arab princes named Aretas. It was by Trajan reduced to subjection to the Roman empire. The city Petra lay, though at a high level, in a hollow three quarters of a mile long and from 800 to 1,500 feet wide, shut in by mountain cliffs, and approached only by a narrow ravine, through which, and across the city’s site, the river winds. There are extensive ruins at Petra of Roman date, which have been frequently described by modern travellers.
Smith's Bible Names Dictionary (1866)