John Trapp on Obadiah 1:19

Verſe 19. And they of the South ſhall poſſeſſe the mount of Eſau,] Thoſe of the South, that is, the tribe of Judah. For Iudaea was divided into five parts, Joſh. 15. whereof one was Southward, toward the coaſt of Edom, ver. 21. Another was in the vale or plain, near unto the Philiſtines, ver. 33. Here then Obadiah ſheweth, that the Jews ſhall not onely recover their ancient inheritances, but alſo much enlarge the ſame: whereby he ſignifieth, that the Church of Chriſt ſhall grow ſo very great, that Jewry ſhall be too narrow for them (ſee Zach. 10.10) the ancient bounders ſhall not receive them. See Num. 24.17. Eſay 11.14. The Goſpel was ſoon ſpread, not onely to the neighbour nations, but to all the ends of the earth: the Edomites, Philiſtines, &c. are onely mentioned, as being better known and more adverſe to the Jews, then other nations were.

and they of the plain, the Philiſtines,] i.e. thoſe five Lordſhips, Gath, Gaza, Aſcalon, Ekron, and Azotus, all which countrey (called Sarona, Acts 9.) Augustus gave to Herod the Aſcalonite; and, after his death, to his ſons; dividing it into Tetrarchies, Luke 3.1.

and they ſhall poſſeſſe the fields of Ephraim, and the fields of Samaria,] All which Hircanus ſubdued, and deſtroyed their Temple built in mount Garizim.

and Benjamin ſhall poſſeſſe Gilead,] that is, ſhall propagate and extend his habitation beyond Iordan: and in reſpect of his exceeding great multitude, ſhall be compelled to hold and poſſeſſe Gilead, all the countrey betwixt Iordan and mount Libanus. Thus Hierom with the Hebrew Scholiaſts, and many others: who do alſo note, that under theſe earthly felicities heavenly are deſcribed: and that all this is chiefly accompliſhed under Chriſt, when as the faithfull are made heirs and lords of all things by Him, who is their Head. See Ezek. 37.16, &c.