枢軸時代
In archaeology, the Iron Age refers to the advent of ferrous metallurgy. The adoption of iron coincided with other changes in some past cultures, often including more sophisticated agricultural practices, religious beliefs and artistic styles, which makes the archaeological Iron Age coincide with the "Axial Age" in the history of philosophy. Although iron ore is common, the metalworking techniques necessary to use iron are very different from those needed for the metal used earlier, and iron was slow-spreading and for long mainly used for weapons, while bronze remained typical for tools, as well as art.