The horse-drawn chariot appears in the 3rd millennium BC, by 2000 BC, in the form of war chariots with spoked wheels, thus being made more maneuverable, and dominated the battlefields. The growing use of the horse, combined with the failure, roughly around 2000 BC, of the always precarious irrigation systems that had allowed for extensive agriculture in the region, gave rise and dominance of pastoral nomadism by 1000 BC, a way of life that would dominate the region for the next several millennia, giving rise to the Scythian expansion of the Iron Age.