12:3 On the east - Which words describe the situation not of the sea of Cinneroth, which was part of the western border of Sihon's dominion, but of the plain, which is here said to lie eastward from the sea of Cinneroth, and also eastward from the salt sea. And this was indeed the situation of the plains of Moab, which are here spoken of; they lay between the two seas, that of Cinneroth and the salt sea, and eastward to them both. Sea of the plain - The salt sea was a famous plain, pleasant and fruitful, before it was turned into a sea.
12:1-6 Fresh mercies must not drown the remembrance of former mercies, nor must the glory of the present instruments of good to the church diminish the just honour of those who went before them, since God is the same who wrought by both. Moses gave to one part of Israel a very rich and fruitful country, but it was on the outside of Jordan. Joshua gave to all Israel the holy land, within Jordan. So the law has given to some few of God's spiritual Israel worldly blessings, earnests of good things to come; but our Lord Jesus, the true Joshua, provided for all the children of promise spiritual blessings, and the heavenly Canaan.