'Iron' in the Bible

Yahweh was with Judah; and drove out [the inhabitants of] the hill country; for he could not drive out the inhabitants of the valley, because they had chariots of iron.

The children of Israel cried to Yahweh: for he had nine hundred chariots of iron; and twenty years he mightily oppressed the children of Israel.

Sisera gathered together all his chariots, even nine hundred chariots of iron, and all the people who were with him, from Harosheth of the Gentiles, to the river Kishon.