Joshua 13:9, 16

from Aroer, which is on the edge of the Valley of the Arnon, and the city that is in the middle of the valley, and all the tableland of Medeba as far as Dibon

So their territory was from Aroer, which is on the edge of the Valley of the Arnon, and the city that is in the middle of the valley, and all the tableland by Medeba