יהושע, פרק י״ח, פסוק כ׳

The mapping of the land given to the tribe of Benjamin concludes by sealing the territory with its final boundary. The Jordan River serves as this definitive eastern edge, stretching across the entire width of the tribal land on that side [רש"י]. Acting as a natural barrier, the river firmly encloses the eastern front of the territory [מצודת דוד, ביאור שטיינזלץ].

With this final line drawn, the mapping of the area is complete, summarizing both the land divided among the families of the tribe and the outer limits enclosing it [מצודת דוד]. The specific pairing of the territory's internal inheritance with its external borders points to the unique nature of Benjamin's land [מלבי"ם]. When detailing the lands of most other tribes, the focus remains solely on the inheritance itself, listing specific cities without outlining the surrounding perimeter. Conversely, in the case of the tribe of Judah, the borders and the inheritance are treated as separate concepts. This separation occurs because Judah's initial boundaries included land that was later given to the tribe of Simeon, meaning their outer boundaries did not perfectly match their actual, final inheritance [מלבי"ם].

Benjamin's territory, however, remained completely whole and exclusive. Not a single foreign tribe was granted land from within its borders. Because of this exclusivity, the two concepts are bound tightly together in the final summary of the land: the inheritance represents the specific cities within the territory, while the borders represent the unbroken outer envelope that perfectly encloses them [מלבי"ם].