Iron Did Not Replace Bronze
The earlier Iron Age had seen the change that gave the period its name: the introduction of iron and the decline of bronze use. However, although bronze use declined at the end of the Bronze Age, iron did not immediately become common in many areas of north-west Europe. Only after around 400 BCE did the use of iron really take off, at which point bronze also started to become common again, together with items of gold and silver. Iron did not replace bronze, but repositioned it within a suite of materials that was available to Iron Age people. Not only were there changes in the metals used, but the styles of objects shifted dramatically: around 500 BCE a newly complex style of objects emerged that is often termed Celtic art, which was found between Ireland and western Russia, linking the whole of Europe in a common set of styles. Celtic art…like the Scythian art…derived from an animistic, indeed magical, engagement with the world.
— Magic: A History, p. 226