דברים, פרק ג׳, פסוק ט״ז

The distribution of territories on the eastern side of the Jordan River reveals fundamental differences in how the various tribes acquired their land. While half the tribe of Manasseh earned their territory through independent conquest, the tribes of Reuben and Gad received their region because they explicitly requested it to support their large flocks of livestock [מלבי״ם].

However, the specific order in which Moses distributed these lands was not a matter of chance; it was driven by a deep spiritual vision. Moses recognized that the eastern region lacked a strong foundation of Torah study. To resolve this, he delayed granting the territories to Reuben and Gad until he could persuade the families of Machir and Jair from the tribe of Manasseh to settle there. Because these families were leading Torah scholars and heads of academies, Moses relied on them to illuminate the area with their wisdom. Only after these scholars agreed and received a large portion of land did Moses finalize the borders for Reuben and Gad. This deliberate sequence serves as an enduring lesson about the supreme importance of choosing to live in an environment rich in Torah [העמק דבר].

Geographically, the new territories were defined by the area's major waterways. The land given to Reuben and Gad was situated next to natural boundaries, specifically the Arnon River, which formed the border with Moab, and the Jabbok River, which marked the border with Ammon [רלב״ג, ביאור שטיינזלץ].

When determining the precise line of these river borders, different perspectives emerge. The primary approach among commentators is that the tribes' ownership included the entire river itself, with their territory extending past the water to the opposite riverbank [רש״י, מזרחי, שפתי חכמים, גור אריה]. In contrast, other scholars view the boundary more strictly, arguing that the near bank of the river served as the absolute limit of the territory, with no ownership extending beyond the water's edge [אבן עזרא, העמק דבר, ביאור שטיינזלץ].