Albert Barnes Commentary Joshua 15:9

"and the border extended from the top of the mountain unto the fountain of the waters of Nephtoah, and went out to the cities of mount Ephron; and the border extended to Baalah (the same is Kiriath-jearim);" — Joshua 15:9 (ASV)

Nephtoab is probably the modern “Ain Lifta,” two miles and a half northwestward of Jerusalem; and Mount Ephron is conjecturally connected with the city Ephrain (2 Chronicles 13:19) or Ophrah (Joshua 18:23).