"The Iron Age itself came very early to Africa, probably around the sixth century B.C.E...."
Richard Hooker, historian
Steel was first produced in carbon furnaces in sub- Saharan East Africa, around 1500 B.C.E. Steel is an alloy of iron and 0.2-2.4 percent carbon. It can also contain trace elements such as vanadium, manganese, or tungsten. The carbon acts as a hardening agent and prevents the lattices of iron crystals from sliding past each other. The more carbon present in steel, the harder it is, but this is at the expense of increased brittleness. By controlling the exact ratio of iron to carbon and other elements, the properties of the steel can be tuned to those needed for a specific function. Damascan steel (also known as Wootz steel) was famed for its strength and ability to keep an edge. It actually originated from India around 300 b.c.e. before being widely exported; it was identified by its banded appearance. Recent studies .of blades made with Wootz steel have found that they contain carbon nanotubes that contributed to their legendary properties. Unfortunately, the process for making the steel died out in the eighteenth century after the necessary ores were depleted.
Modern steel making took off in Europe in the late 1850s with the invention of the Bessemer process. The key element of this process was the removal of impurities via oxidation, achieved by blowing air through the molten iron. For the first time this allowed cheap production of steel on an industrial scale.