Rashi: It is [a city] from Pelishtim.

Malbim: The three are idolatry, Arayos and murder. The fourth was "Galus Shelemah Lehasgir le'Edom."

Rashi: Galus of Yisrael will be a complete Galus ? not one will escape. They stood on the roads, seized refugees and handed them over [to Edom]. So did Anshei Tzor, and [the neighbors] in all four directions in Churban Sheni (Sifri Ha'azinu 322). Azah is to the south, Tzor is to the north, Damesek is to the east, and Araviyim are to the west ¹ ? "Masa ba'Arav ba'Ya'ar Talinu Orechos Dedanim" (Yeshayah 21:13).

Radak: This refers to Churban Sheni. Titus and his camp were mostly Edomim. We do not find a total Galus in Churban Rishon.

Malbim: At the time of the Churban, Edom stood at the border to cut off refugees, like it says in Ovadyah. Many fled to the west, the way of Eretz Pelishtim. Pelishtim handed them over to the enemy, in order that it will be a full Galus, and no one will escape.