Rabbah was the only important town belonging to the Ammonites. It has become literally a stable for the camels of the wandering Bedouins. In the parallel clause the “Ammonites” are put for the land which they inhabit.
Related Commentaries of Ezekiel 25:5
Ezekiel 25:5
5 And I will make Rabbah a stable for camels, and the Ammonites a couchingplace for flocks: and ye shall know that I am the LORD.