Then it goes down westward to the territory of the Japhletites, as far as the territory of Lower Beth-horon, then to Gezer, and it ends at the sea.
Though Joseph was one of the younger sons of Jacob, yet he was his eldest by his most just and best beloved wife Rachel, was himself his best beloved son, and had been the greatest ornament and support of his family, kept it from perishing in a time of famine, and had been the shepherd and stone of Israel, and therefore his posterity were very much favoured by the lot.
Commenting on Joshua 16:1-4
And goeth down westward to the coast of Japhleti,.... This place is now unknown, though no doubt well known to the sons of Joseph, when this lot fell to them, and its border was described: unto the coast of Bethhoron the nether: so called to distinguish it from Bethhoron the upper, Jos 16:5; this was about twelve miles from Jerusalem; See Gill on Jos 10:10...
And goeth down westward to the coast of Japhleti, unto the coast of Bethhoron the nether, and to Gezer: and the goings out thereof are at the sea. (b) Of their inheritance.