Numbers 21:13

13 From there they traveled and camped on the other side of the Arnon, in the desert; this river comes out of the territory of the Emori; for the Arnon is the boundary between Mo'av and the Emori.

Numbers 21:13 Meaning and Commentary

Numbers 21:13

From thence they removed, and pitched on the other side of
Arnon
A river on the borders of Moab:

which is in the wilderness that cometh out of the coasts of the
Amorites;
according to Jarchi, they went round the land of Moab, all to the south and east, and came not into the border of Moab, as Jephthah said, ( Judges 11:18 ) but before they came hither they had a station at Almondiblathaim, ( Numbers 33:46 Numbers 33:47 )

for Arnon is the border of Moab, between Moab and the Amorites;
a river which divided these two countries, and bounded them; and Moses is the more particular in this account, to show that the Israelites took nothing from the Moabites, but what the Amorites had taken from them, they being charged not to distress the Moabites and Ammonites, ( Deuteronomy 2:9 Deuteronomy 2:19 ) , see Jephthah's defence, ( Judges 11:15-27 ) .

Numbers 21:13 In-Context

11 From Ovot they traveled and camped at 'Iyei-Ha'avarim, in the desert fronting Mo'av on the east.

12 From there they traveled and camped in Vadi Zered.

13 From there they traveled and camped on the other side of the Arnon, in the desert; this river comes out of the territory of the Emori; for the Arnon is the boundary between Mo'av and the Emori.

14 This is why it says, in the Book of the Wars of ADONAI, ". . . Vahev at Sufah, the vadis of Arnon,

15 and the slope of the vadis extending as far as the site of 'Ar, which lie next to the territory of Mo'av."