Or HaChaim on Genesis 14:1/אור החיים על בראשית י״ד:א׳

1 ויהי בימי אמרפל, It was during the reign of Amrafel, etc. The reason the Torah introduces this chapter here is to show that these four kingdoms were the super-powers during that period. Once we have been informed of the exploits of these kings, Abraham's victory when he rescued Lot can be seen in its proper perspective.