The Iron Age (800 BC-100 AD) took its name from, well, iron. This kickstarted a number of technological and social changes, with centuries-old Bronze Age (2200-800 BC) civilizations based on copper and tin falling prey to invincible newcomers who wielded formidable iron weapons.

But how did people make iron in the first place? Did they suddenly have access to technology that could raise the temperature high enough to melt iron?

Well, no. Instead, people came up with an ingenious way of using existing technology in a radically different way, as Jason Almendra explains on Quora. They sourced the metal from bog iron or iron ore, both of which had been known for centuries. Now, however, they realized they could ground this to a powder. They then lit a bloomery with charcoal and raised the temperature using bellows.

Iron Age metallurgists alternated adding charcoal and iron…