The Israelites travel to the east of Moab, through the wilderness, specifically to avoid encountering them. And yet, we are told that they travel through Ar-Moab, and even buy food and water from the locals. Do they walk through Moabite territory or not?
An ancient quote, preserved in Jephthah’s speech to the King of Ammon, gives us a clue into the methods of the Torah’s redaction and the status of pre-pentateuchal sources.
To avoid saying that Israel conquered the territory of their Moabite cousins, and that Reuben and Gad may once have been Moabite tribes, the Torah claims that when the Israelites arrived, the land was occupied by Amorites and ruled by King Sihon.