Some 2km south of Dhiban, the vast canyon of Wadi Mujib opens up spectacularly in front, over 500m deep and 4km broad at the top. Just over the lip of the gorge is a small rest stop and viewing platform. The dramatic canyon is an obvious natural focal point, and in biblical times, Arnon, as it was named, was the heartland of Moab, although with shifts in regional power it frequently marked a border between tribal jurisdictions; today, it divides the governorates of Madaba and Karak. The sheer scale of the place takes your breath away, with vultures, eagles and kestrels wheeling silently on rising thermals all around, and the valley floor to the right losing itself in the mistiness of the Dead Sea. The broad, flat plain of the wadi bed, now dammed, is noticeably hotter and creaks with frog calls.