Joshua 13:8, 10, 24-28

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

all the cities of Sihon king of the Amorites, who reigned in Heshbon, as far as the border of the children of Ammon

Moses also had given an inheritance to the tribe of Gad, to the children of Gad according to their families. Their territory was Jazer, and all the cities of Gilead, and half the land of the Ammonites as far as Aroer, which is before Rabbah, and from Heshbon to Ramath Mizpah and Betonim, and from Mahanaim to the border of Debir, and in the valley Beth Haram, Beth Nimrah, Succoth, and Zaphon, the rest of the kingdom of Sihon king of Heshbon, with the Jordan as its border, as far as the edge of the Sea of Chinnereth, on the other side of the Jordan eastward. This is the inheritance of the children of Gad according to their families, the cities and their villages.