“It came to pass after this also, that the children of Moab, and the children of Ammon, and with them other beside the Ammonites, came against Jehoshaphat to battle.”
King James Version (KJV)
20:2 The sea - The dead sea, beyond which mount Seir lay. Syria - Largely so called, and so it includes the Moabites and Ammonites. And it may be thus expressed, to intimate that they came by the instigation of the Syrians, to revenge themselves of Jehoshaphat for joining with Ahab against them.