Charles Ellicott Commentary Genesis 14:8

"And there went out the king of Sodom, and the king of Gomorrah, and the king of Admah, and the king of Zeboiim, and the king of Bela (the same is Zoar); and they set the battle in array against them in the vale of Siddim;" — Genesis 14:8 (ASV)

They joined battle with them. —Hebrew, they set themselves in array against them. As the five kings left their cities to do battle with the invaders “in the vale of Siddim,” it is clear, as was said in Genesis 14:3, that the vale embraces a far wider area than merely the site of the five cities.