Of all the china's early irons, the majorities, whose total amount has accumulated to more than 40 pieces since the 1970's,
are excavated from the
Chu state, and the date assigned to the earliest appearance is suggested as early as the middle phase of the middle Spring and Warring period. The earliest Chu irons, founded from the western Hubei region, are mainly in forms of agricultural implements and small utensils with cutting-edge. By the late Spring and Autumn period, Chu has already developed the techniques to cast irons. At the beginning of the Warring States period, irons changed dramatically, such as large container, long sword and other new shapes of irons appeared at this period. Deliberately-produced iron vessels and bronze ding tripods with iron feet were popular during the middle Warring States period. In short, irons debuted in the Chu state at
the middle Spring and Autumn period, and the society stepped into a new Iron Age by the interim between the Spring and Autumn and the Warring States period.