This ancient song may have been an old Amorite ballad about the victories of King Sihon. It may have celebrated his power and success.
Other interpreters believe that Israelite singers wrote the song later. In this view, it was a taunt song meant to mock Sihon’s defeat and celebrate Israel’s victory.
The flow of the story from Numbers 21:26 to 21:27 supports the first view. Israel may have taken an older Amorite song and applied it to their own victory. Sihon and the Amorites had once defeated Moab. Now Israel had defeated them. Compare Judges 11:12–28.