במדבר, פרק כ״ו, פסוק כ״ט

As the Israelites prepare to enter the land, a new census takes place to count the people. In a shift from the usual pattern, Manasseh is counted before his brother Ephraim. This change in order happens for a few key reasons [חזקוני]. First, the population of Manasseh's families has grown to outnumber Ephraim's, a reversal from the earlier count. Second, the purpose of the counting has changed. The first census organized the physical layout of the camp, where Ephraim served as the lead tribe for their banner. Now, the counting is focused on dividing the land, and half the tribe of Manasseh is destined to receive their territory first, settling on the eastern side of the Jordan River.

The central family line of the tribe traces through Manasseh's son, Machir. Although Manasseh had other sons, the entire tribal family takes its primary identity from Machir because he was the firstborn and the most prominent among them [העמק דבר].

From Machir, the lineage branches out into eight distinct families. One family takes Machir's own name, another is named after his son Gilead, and the remaining six families are named after Gilead's six sons [חזקוני]. Just as Manasseh's broader family was identified through a single prominent son, Machir also had other children, yet his descendants are primarily identified through Gilead [העמק דבר]. Over time, the Gilead family achieved such a unique and elevated status that an entire geographic region was eventually named in their honor [ביאור שטיינזלץ].