Not merely an art medium, charcoal also played a pivotal role in the technological development of man. Used as a fuel source to enable people to smelt and work metals, it was and is an important part of history: both in use for various tools and recording it as seen in the cave drawings above.
Charcoal production and metallurgy go hand in hand. Early attempts to smelt metal using wood were unsuccessful, because you have to have a very high temperature. When you burn regular wood, water and other volatiles are burnt off, limiting the temperature of the fire. Charcoal, however, can produce a much higher temperature with very little smoke. Originally, oxide copper ores were the first reduced with charcoal which began the Bronze Age. The charcoal itself was likely produced using a rudimentary pit kiln, where wood is burnt very slowly and covered with soil. This method then evolved to something known as the forest kiln, a much more efficient way of rendering the charcoal that is still used to this day.