Chinese cast-iron technology

Timeline

1. c. -600–-400States of the Central Plains · Central PlainsIron use appeared in China in the late Spring and Autumn, initially mainly forged bloom iron; by the early Warring States ironmaking activity increased, laying the technical foundation for liquid pig-iron smelting in blast furnaces.
2. c. -400–-221Ironmaking centers of Zhao, Chu, Qi, and others · Handan areaIn the mid-to-late Warring States, pig-iron smelting and annealing technology matured; iron-mold casting and stacked casting greatly increased output of farm tools and weapons; states established government-run ironworks, and ironware became a key resource in military and economic competition.
3. -221–1Guanzhong and ironmaking offices nationwide · ShaanxiQin brought ironmaking under state control; Western Han established iron officials and the salt-and-iron monopoly, and cast-iron technology spread nationwide through military-agricultural colonies, migration, and weapons manufacture, with iron plows and hoes profoundly changing agricultural productivity.