Numbers 21:13

21:13 From there they moved on and camped on the other side of the Arnon, in the wilderness that extends from the regions of the Amorites, for Arnon is the border of Moab, between Moab and the Amorites.

Numbers 21:26

21:26 For Heshbon was the city of King Sihon of the Amorites. Now he had fought against the former king of Moab and had taken all of his land from his control, as far as the Arnon.