Numbers 21:24-26

24Then Israel struck the king of the Amorites with the edge of the sword and took possession of his land from the Arnon to the Jabbok, as far as the Ammonites, for the boundary of the Ammonites was strong.

25Israel took all these cities, and settled in all the cities of the Amorites, in Heshbon and in all its towns.

26For Heshbon was the city of Sihon, king of the Amorites, who had fought against the former king of Moab and had taken all his land out of his hand, as far as the Arnon.