and to the Reubenites and Gadites I gave the territory from Gilead to the Arnon Valley (the middle of the valley was the border) and up to the Jabbok River, the border of the Ammonites.
Having shown how this country which they were now in was conquered, in these verses he shows how it was settled upon the Reubenites, Gadites, and half the tribe of Manasseh, which we had the story of before, Num. 32. Here is the rehearsal. 1.
Commenting on Deuteronomy 3:12-20
The plain also, and Jordan,.... The plain by Jordan, the plains of Moab on the side of it, together with the river: and the coast thereof; the country adjoining to it: from Chinnereth even unto the sea of the plain, even the salt sea; that is, from Gennesaret, as the Targums of Onkelos and Jonathan, called the land of Gennesaret, Mat 14:34, from thence to...
from Gilead--that is, not the mountainous region, but the town Ramoth-gilead, even unto the river Arnon half the valley--The word "valley" signifies a wady, either filled with water or dry, as the Arnon is in summer, and thus the proper rendering of the passage will be--"even to the half or middle of the river Arnon" (compare Jos 12:2).