Deuteronomy 4:41-4:49

Then Moses set aside three cities on the east side of the Jordan to which a manslayer could escape, one who unwittingly slew a fellow man without having been hostile to him in the past; he could flee to one of these cities and live: Bezer, in the wilderness in the Tableland, belonging to the Reubenites; Ramoth, in Gilead, belonging to the Gadites; and Golan, in Bashan, belonging to the Manassites. This is the Teaching that Moses set before the Israelites: these are the decrees, laws, and rules that Moses addressed to the people of Israel, after they had left Egypt, beyond the Jordan, in the valley at Beth-peor, in the land of King Sihon of the Amorites, who dwelt in Heshbon, whom Moses and the Israelites defeated after they had left Egypt. They had taken possession of his country and that of King Og of Bashan--the two kings of the Amorites--which were on the east side of the Jordan from Aroer on the banks of the wadi Arnon, as far as Mount Sion, that is, Hermon; also the whole Arabah on the east side of the Jordan, as far as the Sea of the Arabah, at the foot of the slopes of Pisgah.