See the marginal references. There are many indications found in this and the next chapter that the text is in great disorder, and many of the places are still unknown.
Joshua 18:14
And compassed the corner - Render “and turned on the west side southward.” The meaning is, that at lower Beth-horon the northern boundary-line of Benjamin curved round and ran southward - Beth-horon being its extreme westerly point.
Joshua 18:21
The “Valley of Keziz,” or “Emek-Keziz,” is perhaps the “Wady el Kaziz,” at no great distance east of Jerusalem.
Joshua 18:22
Zemaraim, i. e. “two wooded hills,” is supposed to be the ruins called “Es-Sumrah,” on the road from Jerusalem to Jericho.
Joshua 18:23
Ophrah (Joshua 15:9 note), to be distinguished here and in 1 Samuel 13:17 from the Ophrah of Judges 6:11, is probably the Ephrain of 2 Chronicles 13:19, and the Ephraim of John 11:54. It is conjecturally identified with “Et-Taiyibeh,” on the road from Jerusalem to Bethel.
Joshua 18:24
Gaba - This name, like Gibeah, Gibeon, etc. Joshua 9:3, indicates a town placed on a hill, and occurs repeatedly in various forms in the topography of Palestine. Gaba is the Gibeah (if 1 Samuel 13:15-16; 1 Samuel 14:5, where the Hebrew has גבע Geba‛ which is undoubtedly the correct reading throughout. The city was one of those assigned to the Levites Joshua 21:17, and lay on the northern border of Judah. It is identified with the modern “Jeba,” lying on the side of a deep ravine opposite to Michmash (“Mukhmas”). The famous “Gibeah of Saul,” or “Giheah of Benjamin” (the Gibeath of Joshua 18:28) lay at no great distance southwest of Geba, on the high road from Jerusalem to Bethel, and is probably to be looked for in the lofty and isolated “Tulcil-el-Ful.”
Joshua 18:25
Ramah - i. e. “lofty;” probably the native town and abode of Samuel 1 Samuel 1:19; 1 Samuel 25:1. Its exact site is uncertain.
Joshua 18:26
Mizpeh - See Joshua 11:3. Not the Mizpeh of Joshua 15:38, but the place where Samuel judged the people and called them together for the election of a king 1 Samuel 7:5-16; 1 Samuel 10:17. In the Chaldaean times it was the residence of Gedaliah 2 Kings 25:22; Jeremiah 40:14. Its site is identified with “Neby Samwil,” about five miles northwest of Jerusalem.