C. F. Keil and Franz Delitzsch on Genesis 14:3

Gen 14:3

“All these (five kings) allied themselves together, (and came with their forces) into the vale of Siddim (השׂדּים, prob. fields of plains), which is the Salt Sea;” that is to say, which was changed into the Salt Sea on the destruction of its cities (Gen 19:24-25). That there should be five kings in the five cities (πεντάπολις, Wis. 10:6) of this valley, was quite in harmony with the condition of Canaan, where even at a later period every city had its king.