Deuteronomy 4:41-49

Then Moses set apart three cities [of refuge] beyond the Jordan toward the rising of the sun (eastward), so that someone who committed manslaughter could flee there, [that is, a person] who killed his neighbor unintentionally and without previously having hostility toward him, and that by escaping to one of these cities he might [claim the right of asylum and] save his life: Bezer in the wilderness on the plateau for the Reubenites, and Ramoth in Gilead for the Gadites, and Golan in Bashan for the Manassites. This is the law which Moses placed before the sons of Israel; these are the testimonies (legal provisions) and the statutes and the judgments which Moses spoke to the sons of Israel when they came out of Egypt, beyond the Jordan in the Valley opposite Beth-peor, in the land of Sihon king of the Amorites who lived at Heshbon, whom Moses and the sons of Israel defeated when they came out from Egypt. They took possession of his land and the land of Og king of Bashan, the two kings of the Amorites, who reigned across the Jordan to the east, from Aroer, which is on the edge of the valley of the [river] Arnon, as far as Mount Sion (that is, Hermon), with all the Arabah (desert lowlands) across the Jordan to the east, even as far as the sea of the Arabah (the Dead Sea), at the foot of the slopes of Pisgah.