2 Chronicles 20:1, 23

Now it came about after this that the sons of Moab and the sons of Ammon, together with some of the Meunites, came to make war against Jehoshaphat.

For the sons of Ammon and Moab rose up against the inhabitants of Mount Seir destroying them completely; and when they had finished with the inhabitants of Seir, they helped to destroy one another.