Middle of the river — It is not unusual even among us, for a river to be divided between two lords, and for their territories or jurisdictions to meet in the middle of the river: and besides, here is a very particular reason for this expression, because the city Ar, which was no part of Sihon's dominions, but belonged to the Moabites, Deuteronomy 2:9, Deuteronomy 2:18, was in the middle of the river Arnon, Deuteronomy 2:36, Deuteronomy 3:16, and therefore the middle of the river is properly here mentioned, as the bound of Sihon's dominion on that side. Half Gilead — Heb. and the half Gilead, that is, half of the country of Gilead; this doth not denote the bound from which his dominion began, but the country, over which his dominion was, which began at Arnon, and took in half Gilead, and ended at Jabbok, beyond which was the other half of Gilead which belonged to Og.
Related Commentaries of Joshua 12:2
Joshua 12:2
2 Sihon king of the Amorites, who dwelt in Heshbon, and ruled from Aroer, which is upon the bank of the river Arnon, and from the middle of the river, and from half Gilead, even unto the river Jabbok, which is the border of the children of Ammon;