Deuteronomy 3:12-16

At that time we took this land to be our own. I gave the people of Reuben and Gad the land from Aroer by the Arnon Ravine, as well as half of the mountain country of Gilead and the cities in it. To the people of East Manasseh I gave the rest of Gilead and all of Bashan, the kingdom of Og. (The area of Argob in Bashan was called the land of the Rephaites. Jair, a descendant of Manasseh, took the whole area of Argob, all the way to the border of the Geshurites and Maacathites. So that land was named for Jair, and even today Bashan is called the Towns of Jair.) I gave Gilead to Makir. I gave the Reubenites and the Gadites the land that begins at Gilead and goes from the Arnon Ravine (the middle of the Arnon is the border) to the Jabbok River, which is the Ammonite border.