Why does it say that they returned the cities?
Radak: Yehudah captured them initially, like it says at the beginning of Sefer Shoftim. Afterwards, Pelishtim captured them from Yehudah. Now in the days of Shmuel, they returned them.
Malbim: They were afraid to enter Yisrael's border, so they returned the cities by themselves. Since Hashem struck them whenever Yisrael fought them, they returned also the cities from Ekron to Gas, which had been in their hands for a long time.
Why does it mention Emori? There were not wars with Emori then, only with Pelishtim!
Radak: Perhaps when Pelishtim fought with Yisrael, also other Emori'im who remained in the land fought with Bnei Dan, like it says in Shoftim (1:34) "va'Yilchatzu ha'Emori Es Bnei Dan." When they saw that Pelishtim were subdued, also they were subdued and made peace with Yisrael.
Malbim: When the Emori'im saw that others ruled over Yisrael, they joined with them. This was not so in the days of Shmuel.
