Numbers 21:31
Thus Israel settled in the land of the Amorites.
Numbers 32:33-42
So Moses gave to them, to the sons of Gad and to the sons of Reuben and to the half-tribe of Manasseh the son of Joseph, the kingdom of Sihon, the king of the Amorites and the kingdom of Og, the king of Bashan, the land with its cities and territories, the cities of the surrounding land.
Deuteronomy 3:16-17
To the Reubenites and Gadites I gave the territory from Gilead as far as the Valley of Arnon, with the middle of the Valley as a boundary, and as far as the Jabbok River, the boundary of the sons of Ammon;
Joshua 12:1-6
Now these are the kings of the land whom the sons of Israel defeated, and whose land they possessed beyond the Jordan toward the east, from the valley of the [river] Arnon to Mount Hermon, and all the Arabah [plain] to the east:
Joshua 13:8-12
With the other half-tribe [of Manasseh], the Reubenites and the Gadites received their inheritance which Moses gave them beyond the Jordan eastward, just as Moses the servant of the Lord gave to them;