Deuteronomy 2:23

And the rest of the escaped of the Kenaanah which dwelt in the cities of Dephia to Gaza, the Kapotkaee who came out of Kapotkaia destroyed them, and dwelt in their place.

as far as Gaza. This is mentioned because the region had once belonged to the Philistines, and a covenant was in force between Abraham and Avimelekh (“you will not deal falsely with me, nor with my son, nor with my grandson” [Genesis 21: 23]). Scripture thus relates that the Avvim had taken Gaza [Ḥullin 60b].

AND THE AVIM THAT DWELT IN VILLAGES. Scripture is stating of the Avim that dwelt in villages — without a wall around them as far as Gaza which was the Canaanite border, as it is said, And the border of the Canaanite was from Zidon, as thou goest toward Gerar, unto Gaza — the Caphtorim that came forth out of Caphtor destroyed them and they dwelt in their stead. Now the Caphtorim were descendants of Mitzraim, Verses 13-14. and their land was not part of the gift given to Abraham; nevertheless their land was possessed by Israel because the Caphtorim had conquered it from the children of Canaan. The verse stating with reference to the land of the Philistines, for unto thee [Isaac], and unto thy seed, I will give all these lands, 26:3. was said for this reason: that the land [of the Philistines] originally belonged to the children of Canaan. Therefore, in the days of Joshua Israel drove out the five lords of the Philistines: the Gazite, the Ashdodite, the Ashkelonite, the Gittite, and the Ekronite; also the Avim, for they all dwelled within the Canaanite border — in Gaza, Ashkelon, Ashdod, and in Ekron. They [the lords] were called by the name of their place [i.e., the Gazite, the Ashdodite etc. because, although they were foreigners, after their conquest of these five Canaanite towns, they adopted their names], for they destroyed the Avim who were of the children of Canaan who dwelled within the border of the Canaanite from Zidon, as thou goest toward Gerar, unto Gaza, and they abode in their stead. Zidon also belonged to the Philistines, as it is written, And also what are ye to Me, O Tyre, and Zidon, and all the regions of Philistia?
In my opinion the Avim are identical with the Hivites [who were of the children of Canaan], for such is the customary way of Scripture to alter names, as we have said, so long as they indicate the same meaning, and “the serpent” (the Hivites), which is of the term chivah — a snake. ye’aveit (curves) itself.. Thus the Chivim are identical with the Avim, as both names suggest the snake and its characteristic of crawling crookedly. And in Bereshith Rabbah [we find the following text]: “Said Rabbi Eleazar the son of Rabbi Shimon: They were as expert in [tasting] earth [to determine which crops it is capable of producing] as the serpent [whose only food is the earth]. In the Galilee they call chivya (a serpent) …

כפתורים היוצאים מכפתור השמידם וישבו תחתם. Knowing history you will know that G’d will give you the land that He has sworn to your ancestors.

והעוים היושבים בחצרים עד עזה, even though the latter belonged to the descendants of Esau or the Philistines with whom Avraham had made a solemn non aggression pact, the Israelites were not now denied the right to conquer these lands. The reason they could do so now was that the Philistines no longer owned the land in question כפתורים היוצאימ מכפתור, the Cretans emigrating from Crete because their island could not contain them all and who were seeking “lebensraum,” had annihilated the Avim and replaced them in that land. When the Israelites conquered the land in which Avimelech used to be king, it already had been lost by Avimelech. [Perhaps the reason that this coastal strip was still known as “the land of the Philistines,” long after the Israelites drove out the Canaanites, is the same as when the Torah referred to the land of the descendants of Ammon as “the land of the Refaim,” (verse 20) the latter having been its original owners.” Ed.]

והעוים היושבים בחצרים עד עזה, “and the Avvim who dwelled in villages as far south as Gaza.’ Moses now elaborates where the Chivvi is located. The letters ח and ע are used interchangeably. Do you want to know where to find the Chivvim? They dwell in chatzerim, They were so powerful that they did not bother to live in cities surrounded by a security wall, as they relied on their physical prowess to protect them. The land called: eretz refa-im, was identical with the kingdom of the giant Og, (3,13) it had been promised to Avram and by now the time had come to inherit it and to settle there. However, the land of Moav which the latter had taken away from Eymim, who were giants like the Refaim, are not identical with the Refa-im that G–d promised to Avram, seeing that Moabites called them by a different name,; also the land now occupied by the Ammonites who had dispossessed the Zamzumim and were not the same Refaim as the ones who had lived there hundreds of years earlier.