Joshua 13:8, 10, 24-28

With the other half of the tribe of Manasseh the Reubenites and the Gadites received their inheritance, which Moses gave them, beyond the Jordan eastward, as Moses the servant of the LORD gave them

and all the cities of Sihon king of the Amorites, who reigned in Heshbon, as far as the boundary of the Ammonites

Moses gave an inheritance also to the tribe of Gad, to the people of Gad, according to their clans. Their territory was Jazer, and all the cities of Gilead, and half the land of the Ammonites, to Aroer, which is east of Rabbah, and from Heshbon to Ramath-mizpeh and Betonim, and from Mahanaim to the territory of Debir, and in the valley Beth-haram, Beth-nimrah, Succoth, and Zaphon, the rest of the kingdom of Sihon king of Heshbon, having the Jordan as a boundary, to the lower end of the Sea of Chinnereth, eastward beyond the Jordan. This is the inheritance of the people of Gad according to their clans, with their cities and villages.