In the Northern Song, scientist Shen Kuo (1031 - 1095) wrote of a visit to a forge in Cizhou (in modern Hebei), one of the few places where the skills still survived. It was only when he saw steel being beaten there that he realized what was meant by the expression "true steel."
到了北宋，當時的大科學家沈括曾在《夢溪筆談》一書中說到他造訪磁州鍛坊，觀看煉鐵，才認識所謂「真鋼」。