'Area' in the Bible

“At that time we took possession of this land. I gave to the Reubenites and Gadites the area extending from Aroer by the Arnon Valley, and half the hill country of Gilead along with its cities.

and I gave to the Reubenites and Gadites the area extending from Gilead to the Arnon Valley (the middle of the valley was the border) and up to the Jabbok River, the border of the Ammonites.