John Gill Commentary Joshua 17:6

"because the daughters of Manasseh had an inheritance among his sons. And the land of Gilead belonged unto the rest of the sons of Manasseh." — Joshua 17:6 (ASV)

Because the daughters of Manasseh had an inheritance among his sons Which occasioned such a number of portions; the daughters of Zelophehad are meant, who descended from Manasseh:

and the rest of Manasseh, some had the land of Gilead ; that is, those besides the six families before expressed, namely, the two families of the Machirites and Gileadites, (Numbers 26:29) .