AFAIK Serendib had "large" artisanal "blast" furnaces making "high tech" crucible steel maybe as far back as 300 BC : https://www.nytimes.com/1996/02/06/scienc

AFAIK Serendib had "large" artisanal "blast" furnaces making "high tech" crucible steel maybe as far back as 300 BC : https://www.nytimes.com/1996/02/06/science/ancient-smelter-used-wind-to-make-high-grade-steel.html https://www.nytimes.com/1996/02/06/science/ancient-smelter-u...