Gebal - The Gebal here referred to was probably the same as Gebalene, the mountainous tract inhabited by the Edomites, extending from the Dead Sea southward toward Petra, and still called by the Arabs Djebal. (Gesenius, Lexicon) The word means mountain. Those who are here referred to were a part of the people of Edom.
And Ammon - The word Ammon means son of my people. Ammon was the son of Lot by his youngest daughter, Genesis 19:38. The Ammonites, descended from him, dwelt beyond the Jordan in the tract of country between the streams of Jabbok and Arnon. These also would be naturally associated in such a confederacy. 1 Samuel 11:1-11.
And Amalek - The Amalekites were a very ancient people: In the traditions of the Arabians they are reckoned among the aboriginal inhabitants of that country. They inhabited the regions on the south of Palestine, between Idumea and Egypt. Compare Exodus 17:8-16; Numbers 13:29; 1 Samuel 15:7. They also extended eastward of the Dead Sea and Mount Seir Numbers 24:20; Judges 3:13; Judges 6:3, Judges 6:33; and they appear also to have settled down in Palestine itself, whence the name the Mount of the Amalekites, in the territory of Ephraim, Judges 12:15.
The Philistines - Often mentioned in the Scriptures. They were the ancient inhabitants of Palestine, whence the name Philistia or Palestine. The word is supposed to mean the land of sojourners or strangers; hence, in the Septuagint they are uniformly called ἀλλοφύλοι allophuloi, those of another tribe, strangers, and their country is called γῆ ἀλλοφύλων gē allophulōn. They were constant enemies of the Hebrews, and it was natural that they should be engaged in such an alliance as this.
With the inhabitants of Tyre - On the situation of Tyre, see the Introduction to Isaiah 23. Why Tyre should unite in this confederacy is not known. The purpose seems to have been to combine as many nations as possible against the Hebrew people, and - as far as it could be done - all those that were adjacent to it, so that it might be surrounded by enemies, and so that its destruction might be certain. It would not probably be difficult to find some pretext for inducing any of the kings of the surrounding nations to unite in such an unholy alliance. Kings, in general, have not been unwilling to form alliances against liberty.