Bīntiě (simplified Chinese: 镔铁; traditional Chinese: 鑌鐵) was a type of refined iron, which was known for its hardness. It was often used in the making of Chinese weapons. Bintie was an important article of income in medieval Yuan China as technological advances from the preceding Song dynasty improved Yuan smelting technology. Bintie was referred as "fine steel", due to its high carbon content.^[1][2]