Matthew Poole and continuators on Joshua 12:3

3 And from the plain unto the sea of Cinneroth on the east , and unto the sea of the plain , even the salt sea on the east, the way to Beth-jeshimoth: and from the south under † Ashdothpisgah.

Which words describe the scituation not of the sea of Cinneroth, which was part of the Western border of Sihons Dominion, but of the Plain, which is here said to lye eastward from the sea of Cinneroth, and also eastward from the Salt Sea, as it here follows. And this was indeed the scituation of the Plains of Moab, which are here spoken of, to wit, that they lay between the two Seas, that of Cinneroth and the Salt Sea, and eastward to them both.

The Salt Sea is so called because it was a famous Plain, pleasant and fruitful, before it was turned into a Salt Sea.

Or, on, or towards the South.

Marginal references: Deut. 3. 17.; Or, Teman.; Deut. 3. 17. and 4. 49.; ‡ Or, the springs of Pisgah, or the hill.