Albert Barnes Commentary Joshua 17:16

"And the children of Joseph said, The hill-country is not enough for us: and all the Canaanites that dwell in the land of the valley have chariots of iron, both they who are in Beth-shean and its towns, and they who are in the valley of Jezreel." — Joshua 17:16 (ASV)

The possession by the Canaanites of chariots strengthened and tipped with iron, such as were used by the Egyptians (Exodus 14:7), is named here by the children of Joseph as a reason why they could not take possession of the plains. “The valley of Jezreel” is the broad low valley which sweeps from “Zerin” between the mountains of Gilboa and the range of Little Hermon eastward down to the Jordan. It was most likely in this valley that the host of the Midianites was encamped when attacked by Gideon (Judges 7:1, Judges 7:8).

The great plain of Jezreel, called the plain of Esdraelon (Esdrelom, Judith 1:8), extends from Carmel on the west to the hills of Gilboa, Little Hermon, and Tabor on the east, a distance of full sixteen miles; and its breadth between the rocky mass of southern Palestine and the bolder mountains of Galilee on the north is about twelve miles. Its position, as well as its open area, makes it the natural battlefield of Palestine.