One of the great periods of change in civilization occurred when steel replaced bronze . Yet, it was entirely unknown what gave steel its valuable properties , and for centuries the techniques for making high quality steel were closely held, almost alchemical, secrets. Clearly, iron was its major component, but a myriad of other minor additions were found empirically, and even more mysterious treatments were evolved for cooling the red hot object to room temperature - unlikely manufacturing processes such as adding mixtures of blood, and aging times which depended on the phase of the moon, for example. B.C. Iron was known before this time, but Maddin suggests that it was the discovery of how to make steel that led to the shift. Iron isn't a very useful material.
Steel is an immense improvement over bronze.
Maddin's earliest example of martensite comes from an excavation in 1976. He says the analysis shows a pretty sophisticated manipulation of iron into steel. Arrow indicates flake shown in the next figure. 11th century B.C. knife excavated from a tomb in Idalion, Cyprus. I'm guessing the stiated lines are martensitic twins.