Albert Barnes Commentary 1 Chronicles 2:23

"And Geshur and Aram took the towns of Jair from them, with Kenath, and the villages thereof, even threescore cities. All these were the sons of Machir the father of Gilead." — 1 Chronicles 2:23 (ASV)

Rather, And Geshur and Aram (that is, the Geshurites, Deuteronomy 3:14, and the Syrians) took the villages of Jair from them; that is, they recovered from the new settlers the places that Jair had conquered.

All these belonged to the sons of Machir—Rather, All these were sons of Machir; that is, Segub and Jair, with their descendants, were counted as sons of Machir rather than sons of Hezron, although they were descended from Machir only on their mother’s side. The reason for this seems to have been that they cast their lot with the Manassites and remained in their portion of the trans-Jordanic region.