בראשית יד:ב פירוש: רש״י, רמב״ן, רד״ק וטור הארוך

ברע BERA —Evil (רע) towards God and evil towards mankind (Midrash Tanchuma, Lech Lecha 8).

AND THE KING OF BELA. The reason [why Scripture does not mention his name as it does with the kings of Sodom, et al], is that he ruled over a small city with few men in it and he had no generally recognized reputation.

עשו מלחמה, now the Torah tells of the battle between them in the valley of Sidim. The fact that there had been previous wars resulting in the five kings becoming subservient to the four kings is mentioned only as a backdrop to this war that prompted Avram’s involvement.