יהושע, פרק י״ג, פסוק כ״ה

The drawing of the tribal borders covers a vast stretch of land. This expansive region reaches from Jazer and the various cities of Gilead all the way to Aroer, which sits across from Rabbah.

Included within these borders is half of the Ammonite territory. The primary approach among commentators is that the Israelites did not conquer this land directly from the Ammonite nation. Instead, this specific region, which featured several important cities, had previously been taken by Sihon. When the Israelites defeated Sihon, they gained control of the area. Consequently, it became part of the Israelite inheritance not through a direct conflict with the Ammonites, but as a result of the territory passing into their hands following their victory over Sihon.