Joshua 12:1

Now these [are] the kings of the land which the children of
Israel smote
In the days of Moses, as Jarchi remarks, and as it clearly appears from what follows:

and possessed, their land on the other side Jordan toward the rising
of the sun;
on the east of the land of Canaan:

from the river Arnon unto the mount Hermon, and all the plain on the
east;
Arnon was the border of Moab between them and the Amorites, ( Numbers 21:13 ) ; and from hence to Hermon, a mountain adjoining to Lebanon, lay the country of the two kings of the Amorites after mentioned, ( Deuteronomy 3:8 Deuteronomy 3:9 ) ; and the plain on the east were the plains of Moab, which lay to the east of Jordan.