(Arʹnon).

About halfway down the eastern side of the Dead Sea the deep gorge of the Arnon Valley cuts through the high plateau region. This torrent, the Wadi Mujib (Nahal Arnon), is fed by numerous tributaries (Nu 21:14) and, after the Jordan, is the only important stream emptying into the Dead Sea. The sheer red and yellow sandstone cliffs drop down abruptly to flank the sides of the narrow valley with its small perennial stream of limpid waters, replete with fish. Alongside grow willows, oleanders, and other vegetation in abundance. Where the stream leaves the steep chasm walls to enter the flat shore of the Dead Sea its size varies from 12 to 30 m (40 to 100 ft) in width, with a flow of from 0.3 to 1.2 m (1 to 4 ft) in depth.

The formidable canyon, which, at the top, measures some 3 km (2 mi) in width and is nearly 520 m (1,700 ft) deep, was crossed by only a few passages (Isa 16:2) and hence became an obvious natural boundary. At the time of the Israelite conquest it separated the Amorites on the N from the  Moabites on the S (Nu 21:13), but Jephthah’s message to the Ammonites shows that the side to the N had once been under Ammonite control and had been invaded by the Amorites prior to Israel’s arrival. (Jg 11:12-27) Israel, having skirted the territory of Moab, reached the Arnon, probably at its upper reaches. Attacked by Sihon, the Amorite king, Israel gained the victory and took possession of the land from the Arnon up to the Jabbok. (Nu 21:21-24; De 2:24-36; see JABBOK, TORRENT VALLEY OF.) This first conquest thereafter became the territory of the tribes of Reuben and Gad.​—De 3:16; Jos 12:1, 2; 13:8, 9, 15-28.

Because of Jehu’s failure to walk strictly according to Jehovah’s law, this region was later overrun by the invading forces of Hazael of Syria. (2Ki 10:32, 33) The Arnon is referred to on line 26 of the famed Moabite Stone, King Mesha of Moab there boasting that he had constructed a highway through the valley. Archaeological discoveries give evidence of a number of forts and bridges in the area testifying to the strategic importance of the Arnon. Its name figures in prophecies directed against Moab.​—Isa 16:2; Jer 48:20.