Crucible steel
Damascus blacksmiths had made steel blades with carbon nanotubes long before they were scientifically discovered
This is one of those stories about a technology invented and then forgotten. For example, when the Romans invented concrete and then another civilization reinvented it thousand years later. Well, it turns out that the skilled Damascus blacksmiths had produced blades containing carbon nanotubes at least 400 years before modern science began to understand their strength.