Deuteronomy 2:36

“Of the land that we took over at that time, I gave the Reubenites and Gadites the territory north of Aroer, by the Arnon Gorge, including half the hill country of Gilead, together with its towns.”

Continues the geographical narrative from Deuteronomy 2.

“Also to the Reubenites and Gadites I gave the territory extending from Gilead down to the Arnon Gorge (the middle of the gorge being the border) and as far as the Jabbok River, which is the border of the Ammonites.”

Expands on the geographical details.

“...one king was Sihon king of the Amorites, who lived in Heshbon and ruled from Aroer on the edge of the Arnon Gorge—from the middle of the gorge—to the Jabbok River, which is the border of the Ammonites. That included half of Gilead.”

Recalls the defeat of Sihon and the extent of his territory.

“While Israel occupied Heshbon and its surrounding settlements, Aroer and its settlements, and all the towns along the Arnon for three hundred years, why didn’t you retake them at that time?”

Mentions Aroer and the Arnon in the context of Israel's conquest.

“from the Jordan eastward, all the land of Gilead (the region of the Gadites, Reubenites and Manassites), from Aroer by the Arnon Gorge through Gilead to Bashan.”

Refers to Aroer by the Arnon Gorge, marking a geographical boundary.