What does Joshua 13:31 mean?

It also included half of Gilead, Ashtaroth, and Edrei—the main cities of Og’s kingdom in Bashan. This land was given to the families of Machir, son of Manasseh, for half of his descendants. Joshua 13:31 - Modern Text Bible

(This verse clarifies that only half of Manasseh’s tribe got this land, specifically the descendants of Machir.)