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 21:24
21:24 But the Israelites defeated him in battle and took possession of his land from the Arnon to the Jabbok, as far as the Ammonites, for the border of the Ammonites was strongly defended.