Judges 11:18

Then they went along the wilderness
The wilderness of Paran, which lay along the borders of Edom; they went, according to Jarchi, from the west to the east on the south border of Edom and Moab:

and compassed the land of Edom, and the land of Moab;
all the south of the land of Edom, and all the south of the land of Moab; towards the sunrising, as in ( Numbers 21:11 )

and pitched on the other side of Arnon;
the river Arnon, which, according to Jarchi, was at the east end of the land of Moab, where began the country of Sihon and Og:

but came not within the border of Moab;
so far were they from attempting to take away any part of that land from the king of it, though ill treated by him:

for Arnon was the border of Moab;
which divided between Moab and the Amorites, ( Numbers 21:13 ) .