Deuteronomy 3:8

Sihon and Og ruled Amorite kingdoms east of the Jordan River. Their land stretched from the Arnon River Gorge in the south to Mount Hermon in the north. We captured it all.

Joshua 12:2-6

Sihon king of the Amorites, who lived in Heshbon, and ruled from Aroer, which is upon the bank of the Arnon River, and from the middle of the river, and from half Gilead, to the Jabbok River, which is the border of the children of Ammon;

Joshua 13:9-12

From Aroer, that is upon the bank of the river Arnon, and the city that is in the midst of the river, and all the plain of Medeba to Dibon

Numbers 32:33-42

So Moses gave the tribes of Gad, Reuben, and half of the tribe of Manasseh, son of Joseph, the kingdoms of King Sihon of the Amorites and King Og of Bashan. It was the whole land with its cities and its surrounding territory.

Treasury of Scripture Knowledge

Summary

And we took at that time out of the hand of the two kings of the Amorites the land that was on this side Jordan, from the river of Arnon unto mount Hermon;

Bible References

The land

Numbers 32:33
So Moses gave the tribes of Gad, Reuben, and half of the tribe of Manasseh, son of Joseph, the kingdoms of King Sihon of the Amorites and King Og of Bashan. It was the whole land with its cities and its surrounding territory.
Joshua 12:2
Sihon king of the Amorites, who lived in Heshbon, and ruled from Aroer, which is upon the bank of the Arnon River, and from the middle of the river, and from half Gilead, to the Jabbok River, which is the border of the children of Ammon;
Joshua 13:9
From Aroer, that is upon the bank of the river Arnon, and the city that is in the midst of the river, and all the plain of Medeba to Dibon