The genius of ancient Indians: Inventors of #steel | Indians produced the first true steel, fusing iron with a high amount of carbon. They did this by sealing iron and charcoal into clay containers called crucibles, and roasting these at extremely high temperatures in furnaces [~400 BC]
https://www.reddit.com/r/CelebratingIndia/comments/toh668/the_genius_of_ancient_indians_inventors_of_steel/
https://indianexpress.com/article/parenting/learning/genius-ancient-indians-inventors-damascus-steel-5553542/