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; From Aroer - Aroer was situated on the western side of the river Arnon, in the middle of the valley through which this river takes its course. The kingdom of Sihon extended from the river Arnon and the city of Aroer on the south to the river Jabbok on the north.
And from half Gilead - The mountains of Gilead extended from north to south from Mount Hermon towards the source of the river Arnon, which was about the midst of the extent of the kingdom of Sihon: thus Sihon is said to have possessed the half of Gilead, that is, the half of the mountains and of the country which bore the name of Gilead on the east of his territories.
River Jabbok - This river has its source in the mountains of Gilead; and, running from east to west, falls into Jordan. It bounds the territories of Sihon on the north, and those of the Ammonites on the south.