a list of the essence of the collection -j9九游会备用

the age of iron is a new epoch after the bronze age, marked by iron smelting and iron tool making. the iron age is the extremely important period in human history. the making of iron implements led to a big revolution, pushing forward the development of agricultural productivity greatly, in the development of chinese science and technology and agricultural implements, promoting social progress and accelerating the collapse of slavery. therefore, farm tools of iron are marked as a new epoch.