יהושע, פרק י״ד, פסוק ג׳

The distribution of land within Canaan builds upon an earlier division that took place before the Israelites even crossed the border. Moses had already assigned land to two and a half tribes in the territory captured from the Amorite kings on the eastern side of the Jordan River [שטיינזלץ]. Furthermore, the tribe of Levi was completely excluded from this standard distribution of territory, acting in direct accordance with the command of God [מצודת דוד, שטיינזלץ].

Establishing these historical facts is necessary to understand the current task facing Joshua. With two and a half tribes already settled by Moses, and the Levites receiving no land at all, it would logically seem that only eight and a half tribes should remain in need of territory. Laying out this background creates the foundation for understanding why Joshua is ultimately required to divide the remaining land among nine and a half tribes, a situation that is resolved shortly after [מצודת דוד].