Thimnathah - Probably the same as Timnah. See on Joshua 15:57 (note).
Ekron - A well-known city of the Philistines and the metropolis of one of their five dynasties.

And Elon,.... Of Elon no mention is made elsewhere:
and Thimnathah is a different place from Timnah in the tribe of Judah, Joshua 15:10. Jerom (s) speaks of the Thamnitic country, so called from the village Thamna, which seems to be this:
and Ekron was one of the five principalities of the Philistines, and never possessed by the Israelites; it first fell by lot to the tribe of Judah, and afterwards given to the tribe of Daniel, Joshua 15:45.
(s) De loc. Hebrews. fol. 88. E.

Elon, which is mentioned again in 1-Kings 4:9, with the addition of Beth-hanan, has not yet been traced; according to Knobel, it "may possibly be Ellin, near Timnath and Beth-shemesh, mentioned by Robinson in his Pal. vol. iii. App." Thimna (Thimnathah) and Ekron, on the boundary of Judah (see at Joshua 15:10-11).