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.