C. F. Keil and Franz Delitzsch on 2 Chronicles 20:2

2Ch 20:2

Then they came and announced to Jehoshaphat, sc. messengers or fugitives; the subject is indefinite, and is to be supplied from the context. “Against thee there cometh a great multitude from beyond the (Dead) sea.” מארם also has no suitable sense here, since in the whole narrative nothing is said of enemies coming out of Syria; we should read מאדם with Calmet and others. As the enemy made their attack from the south end of the Dead Sea, the messengers announce that they were come from Edom. “Behold, they are in Hazazon-tamar,” i.e., Engedi, the present Ain Jidy, midway along the west coast of the Dead Sea (see on Jos 15:62 and Gen 14:7), about fifteen hours from Jerusalem.